Types of Outdoor Algae cultivation systems Photobioreators (PBRs)

An Advancements in Algae Cultivation: A Vital Component of…

Introduction and History of Commercial Algae Cultivation:

Algae’s usefulness in food, nutrition, and a variety of other industrial applications has long been recognized. With the rising demand for alternative energy sources, promising applications of algal biomass in biofuel generation have grown in significance. Apart from that, the issue of climate change and rising GHG emissions has driven the market for microalgae-based CO2 sequestration approaches in recent years. This has resulted in highly distinctive innovations in the algae business for improved mass culture. However, it is always interesting to examine the evolution and technological interventions that have occurred in the algae cultivation industry.  

People in several parts of the world have been consuming microalgae and seaweed as a major food source for many centuries. Around 2000 years ago, the Chinese population solved the hunger issue by eating Nostoc, as documented by Janssen et al. in 2002. In 1519, Spanish scientist Hernando Cortez and Conquistadors discovered the microalgae Arthrospira platensis (Spirulina). Initially, it was farmed in Mexico’s alkaline lakes and on the African continent, but now it is commercially grown and collected worldwide. Algae cultivation also occurred in other locations, such as Lake Texcoco in the Valley of Mexico, during the sixteenth century. In 1964-65, Jean Léonard reported the sale of greenish, edible cakes in the local markets of Fort-Lamy in Chad, Africa (Sow, S., & Ranjan, S. 2021). To promote economic recovery during World War II, Japan actively promoted the consumption of proteinaceous algae.

Market of Microalgae

Despite this extensive history, researchers have only domesticated and produced a few wild microalgae species for human food and/or usage. These include Arthrospira platensis (Spirulina), Chlorella vulgaris (Chlorella), and Aphanizomenon. Until a few decades ago, nature’s water bodies rich in naturally growing microalgae were the only sources of consumable microalgae. However, microalgae culture, or artificial farming, is now performed worldwide, and the development of biotechnology to cultivate microalgae began in the middle of the last century (Wang, Y., et al 2021, Spolaore et al. 2006).

According to the research conducted by Dogma Jr. et al. in 1990, Asian countries have always been well known for their significant algae production for food purposes. In the 1980s, Naylor (1976) determined the production of seaweed by various Asian countries. Their estimate revealed that Japan, China, and Korea ranked at the top of the producers list, collectively producing 1,733,500.0 mt of seaweed. Conversely, the Philippines, Indonesia, and India were identified as low producers, with a combined production of approximately 28,000.0 mt of seaweed. During the 1980s, these Asian countries emerged as the major seaweed producers.

Development of the Algae Industry:

In the decades from 1940 onward the development of the algae cultivation industry occurred in the following chronology:

  • The year 1940-1950 – Beginning of commercial algae cultivation projects in European and Asian countries.
  • The year 1950-1960 – The issues first encountered and resolved into the practical aspects of mass cultivation involved essential nutrients, vigorous mixing, and the supply of CO2.
  • The year 1960-1970 – Development in the design and operation of open ponds for mass cultivation and protein-rich microalgal biomass.
  • The year 1970-1980 – R&D for algae for biofuels and Production of algal biomass on a large scale. Growth of the market for algae-based products in Western countries.
  • The year 1980-1990 – Research on emerging products from algae biomass in pharmaceuticals, nutrients, cosmetics, biofuels, etc. Government agencies started supporting R&D programs for biofuels. 
  • The year 1990-2000 – Development of a novel product market for algae-based products and commercial production of algal biomass for food, nutrition, and pharma applications.
  • The year 2000-2010 – Researchers primarily focused on researching mass algae cultivation based on photobioreactors and hybrid cultivation systems. They successfully developed novel algae cultivation systems and demonstrated their potential.
  • The year 2010-2020 – Development of newer industries in the algae sector. Importance algae in air and water treatment introduced along with biofuel production.
  • The current decade (2020-2030) – Novel emerging technology development for algae-based climate mitigation solutions is taking place. Emerging innovators and investors started developing GHG mitigation solutions along with multiple biofuels and cleantech options. 

World Scenario of Algae Technology:

Human diets, functional components, cosmeceuticals, medicines, animal and aquaculture feeds, fatty acids, alginates, carotenoids, wastewater treatment, and biofuels are just a few of the biological and industrial applications for microalgal species. Companies sell cyanobacteria Arthrospira sp., and Chlorella vulgaris not only as protein-rich food ingredients and supplements but also as functional foods, and they generally regard them as safe (GRAS). Because of their high vitamin, mineral, and carotenoid concentrations. While annual global microalgae production is currently modest (5.0 104 tonnes dry matter) in comparison to macroalgae (seaweeds) production (7.5 106 tonnes dry matter), microalgae biomass and bio-actives extracted from it are of great nutritional and economic importance (values at USD 1.25 109 annually).

Importantly, researchers have yet to research, let alone commercialize, the vast majority of the tens of thousands of distinct species that make up the big, polyphyletic group of microalgae. As a result, there is enormous potential in researching and developing microalgae as sources of high-quality, sustainable protein for human meals and dietary supplements (www.bsb.murdoch.edu, McGill 2008, Javed and Farooq, 2013, Sankpa and Naikwade, 2013, Sarwer, A., et al. 2022).

Algae cultivation systems:

Algae can be cultivated in various types of systems, ranging from simple open ponds to complex photobioreactors. These systems have the potential to revolutionize the way we produce algae-based food, energy, and products while mitigating some of the environmental impacts associated with traditional production methods. In this article, we will explore various types of algae cultivation systems, and how they work on a large scale.

Algae cultivation systems are vessels that hold water as a medium and nourish algae by exposing them to plenty of light, which facilitates photosynthesis.

The basic algae cultivation system is equipped with:

  • Growth Vessel: The cultivation vessel with a larger surface area to receive maximum light energy. (Pond Height ≤30cm, Tube ID≤20cm) (Yadala, S., & Cremaschi, S. 2016, Torzillo, G., & Chini Zittelli, G. 2015)
  • Agitation: Mechanical or pneumatic way of vigorous agitation provided with baffles to avoid dead zones inside the system due to lack of proper agitation (de Souza Kirnev, P. C., et al. 2022)
  • Light Source: Suitable Natural or Artificial light source supplying Photosynthetic Photon Flux Density in the range of 26−700 µmol photons m−2 s−1 (Maltsev, Y. et al. 2021)
  • Nutrient Source: Providing necessary nutrients for large-scale algae cultivation projects is a challenging task. Algae Production utilizes mostly inorganic fossil-based NPK fertilizers for the same purpose, but the ever-increasing demand and decreased production could lead to fertilizer scarcity in the future.
  • CO2 Supplementation: Traditionally, photoautotrophs obtain their major carbon source from dissolved CO2, which researchers supply by pneumatically feeding ambient air mixed with or without pure industrial CO2 gas.

Researchers develop algae cultivation systems that range from laboratory-scale experimental studies to outdoor massive production, depending on the scale. For laboratory-scale systems, they mostly use borosilicate glass, which is readily autoclavable for aseptic experimental studies. Additionally, researchers can utilize outdoor cultivation vessels that range from a simple open pond to a complex closed photobioreactor, based on the requirements of the algae strain being grown and the desired final product. The flowchart below presents a clear idea of the types of algae cultivation systems, which researchers classify based on the construction scale and the light source they utilize.

algae cultivation system

Laboratory Scale Algae Cultivation Systems

The successful algae cultivation process starts from a laboratory-scale inoculum development process that involves the transfer of unialgal or even axenic culture of algae from a sterile environment to outdoor non-sterile conditions in a step-by-step manner. This involves the utilization of smaller-level sterile glass liquid vessels like tubes, flasks, and bottles to some liter capacity laboratory scale PBR systems (Borowiak, D., et al.2020). Apart from scaleup, the laboratory-scale algae cultivation system with artificial light illumination can be a highly useful tool for experimentation and research purposes. In order to ensure the system is both efficient and effective, it is important to consider certain factors such as the lighting system and the autoclavability of the equipment.

1. All kinds of glass vessels to grow liquid cultures in a sterile condition

They are preferred over other materials because of their transparency, durability, and ease of cleaning. Here are some common types of glass vessels used in algae cultivation:

Culture Tubes:

Culture tubes have a straighter shape and a smaller volume. These systems are utilized for growing small volumes of algae in a sterile environment, serving as the initial transition point for transferring algal cells from a spent solid growth medium to a fresh sterile liquid medium.

Erlenmeyer Flask:

This is a conical-shaped glass vessel with a narrow neck and a wider base. The narrow neck helps to reduce evaporation and contamination. Researchers commonly use Erlenmeyer flasks for small-scale cultures of algae in the laboratory. These flasks are typically either screw-capped or covered with cotton to ensure the maintenance of internal sterile conditions.

Carboys:

Carboys are large glass containers with narrow necks and wide bases. They are used for growing large volumes of algae in a sterile environment. They are particularly useful for industrial-scale algae cultivation.

Fernbach Flask:

Fernbach flasks have a wider base and a shallower depth than Erlenmeyer flasks. They are used for growing algae cultures that require a lot of aeration, such as those that produce high levels of oxygen.

Bell Jars:

Researchers use bell jars, which are glass domes, to cover Petri dishes or other small glass vessels. These bell jars are employed to establish a sterile environment for growing algae cultures on a small scale.

Regardless of the type of glass vessel utilized, it is crucial to ensure proper cleaning and sterilization before use to prevent contamination of the algae culture. Due to their small sizes, researchers can easily clean, wash, and sterilize them using laboratory equipment. Therefore, basic laboratory glassware has become an important vessel for algae cultivation. As the scale-up process progresses in algae cultivation, larger systems are required to accommodate higher volumes of algae. The required systems for algae cultivation include the following: (Wikipedia contributors. 2023, February 1).  

2. Cylindrical glass vessels

The cylindrical glass vessels, which are bioreactors made of glass, come equipped with the necessary provisions for agitation, temperature control, light illumination, aeration (CO2), and pH. These bioreactors provide a controlled environment for algae cultivation, allowing researchers to optimize the growth conditions and maximize productivity. They are generally of ≤20cm internal diameter making a light path length of 10cm when illuminated from all directions externally as per the standard recommended limit for light penetration. They are mostly illuminated externally with artificial light sources which can be regulated as per the need of the microalgal species growing in it.

This type of system is either mechanically or pneumatically agitated (or with the help of both options) depending upon the shear tolerance and aeration requirement of the microalgae in consideration. They provide optimal conditions for laboratory-scale studies to monitor the effect of light, temperature, and nutrients on algal biomass production as well as their primary and secondary metabolites. They can construct these cylindrical bioreactors to hold different volumes, ranging from milliliters to liters. However, for laboratory-scale studies, it is always operationally feasible to use cylindrical bioreactors with volumes less than 1L.

3. Glass Flat Panels

Glass Flat Panels are another essential type of laboratory-scale algae cultivation system. These panels serve as a thin clamber holding algae between two plates that offer a wide surface area for maximum light exposure for photosynthesis. The light path length through a flat panel is ≥10cm preferred when illuminated from one side. This could be doubled if illuminated from both sides. To ensure accurate experimentation, the panels must be able to withstand the conditions of the cultivation process, including exposure to artificial light and autoclaving.

Glass Panels for algae cultivation have the ability to withstand high temperatures and pressures during autoclaving. Therefore, researchers construct most flat panel systems using borosilicate glass materials and stainless-steel framing to create sturdy models for frequent sterilization processes. Due to its larger surface area, the flat panel system earns recognition for its exceptional light illumination capability. Researchers favor it for conducting experiments that examine the effects of varying light intensities and types on algal growth, lipid production, nutrient consumption rate, and photoinhibition studies.

Open Systems

An open system of algae cultivation involves the growth of algae in open shallow water streams which could be originating from the natural system or artificially prepared. In this system, researchers can cultivate algae in natural water bodies such as lakes, rivers, and oceans, as well as in artificial ponds constructed from concrete, plastic, pond liners, or a variety of materials. The open system of algae cultivation is simple and cost-effective, making it an attractive option for commercial production of algae-based products.

1. Water Lagoon

A lagoon, a type of aquatic ecosystem, is characterized by a shallow body of water that is separated from the open ocean using natural barriers such as sandbars, barrier islands, or coral reefs. An Australian company uses this algae cultivation system. Cognis Australia Pty Ltd is a well-known company that specializes in producing β-carotene from Dunaliella salina harvested from hypersaline extensive ponds located in Hutt Lagoon and Whyalla. These ponds are primarily used for wastewater treatment, and the production of D. salina is a secondary benefit (Spolaore, P., et al. 2006, Curtain, C. 2000, Campbell, P. K., et al. 2009).

2. Open Sea Cultivation (Seaweed)

Open sea cultivation is a method of cultivating seaweed in the open ocean, as well as on a coastal line in shallow water. The seaweed farming industry serves commercial needs for various products such as food, feed, pharma chemicals, cosmetics, biofuels, and bio-stimulants. Seaweed extracts act as bio-stimulants, reducing biotic stress and increasing crop production. Additionally, it presents opportunities for creating animal and human nutrition products that can improve immunity and productivity. Open ocean seaweed cultivation is an eco-friendly technology that doesn’t require land, fresh water, or chemicals. It also helps mitigate the effects of climate change by sequestering CO2.

The open sea cultivation method involves the use of rafts or ropes anchored in the ocean, where the seaweed grows attached to them. This method is widely used for commercial seaweed farming, as it allows for large-scale production and harvesting. The process of open sea cultivation of seaweed involves several steps. First, the intender identifies a suitable site in the ocean based on factors such as water depth, temperature, salinity, and nutrient availability. Once they choose a site, they anchor ropes or rafts in the water and attach seed pieces of seaweed to them using specialized equipment. The seaweed is then allowed to grow for several months, absorbing nutrients from the water and sunlight through photosynthesis. (Peteiro, C., et al. 2014).

3. Raceway Ponds

One of the most common and economic methods of large-scale algae cultivation is in open raceway ponds, which offer several advantages over other cultivation methods. An open raceway pond is a shallow, rectangular-shaped pond used for the cultivation of algae. Because it is designed to circulate water in a continuous loop or raceway, allowing algae to grow in a controlled environment. Open System is a low-cost method of algae cultivation, and it is relatively easy to construct and maintain. Researchers typically line the pond with a synthetic material, such as polyethylene (HDPE) or polyvinyl chloride, to prevent the loss of water and nutrients. They also equip the pond with paddlewheels or other types of mechanical devices to provide mixing and aeration (Klein, B., & Davis, R. 2022).

4. High Rate Algal Ponds (HRAPs)

High-Rate Algal Ponds (HRAPs) are a type of open algae cultivation system that has gained popularity in recent years due to their efficiency and low cost of operation. HRAPs (High Rate Algal Ponds) are shallow ponds, usually ranging from 0.1 to 0.4 meters deep, utilized for cultivating algae. Researchers equip these ponds with a paddlewheel or another type of mechanical agitation system to provide mixing and aeration, thereby facilitating algae growth. The use of HRAP systems is also recommended in wastewater treatment involving algae (Mehrabadi, A. et al. 2015, The Local Government Association-LGA of South Australia).  

5. Revolving Algal Biofilm Reactor (RABR)

The use of revolving disks of polystyrene to produce algal biofilm to reduce nitrogen and phosphorus in municipal wastewater was originally described in the 1980s. (Przytocka-Jusiak et al., 1984). The goal of this research was to create a rotating algal biofilm (RAB) growing method that microalgae producers could use to easily harvest biomass. Algal cells grew on the surface of a substance that alternated between a nutrient-rich liquid phase and a CO2-rich gaseous phase. Scraping biomass from the connected surface saved costly harvesting operations like centrifugation. Cotton sheets outperformed all other attachment materials in terms of algal growth, durability, and cost-effectiveness. Harvest frequency, rotation speed, and CO2 levels were further tuned in a lab-scale RAB system.

The water content of the algal biomass from the RAB system was comparable to that of centrifuged biomass. When compared to a control open pond, an open pond raceway retrofitted with a pilot-scale RAB system resulted in significantly higher biomass productivity. The research indicates that the RAB system is an efficient algal culture system for convenient biomass harvesting and increased biomass productivity (Gross, M., et al. 2013).

RAB Systems by Gross-Wen Technologies:

Currently, industries primarily perform algal cultivation in open ponds or photobioreactors, where they suspend algal cells and harvest them through flocculation and centrifugation. They recently developed a novel attachment-based Revolving Algal Biofilm (RAB) culture system that enables easier biomass harvest and increased biomass productivity. The goal of this study was to assess the efficacy of the RAB system at the pilot scale (durability, algae growth, and shape). The RAB system was successfully tested for a year at a greenhouse plant in Boone, Iowa, USA. The RAB increased biomass productivity by 302% on average when compared to a typical raceway pond, with a maximum biomass productivity (ash free) of 18.9 g/m2-day achieved. The vertical RAB outperformed the triangle RAB in terms of productivity. The research reveals that the RAB, as an efficient algal growing method, has a high potential for commercialization. (Gross, M., & Wen, Z. 2014)

Productivity:

Gross-Wen Technologies have devised a Revolving Algal Biofilm (RAB) growth system, where they bond algal cells to a flexible material that undergoes rotation between liquid and gas phases. In this work, they created different configurations of the RAB system at pilot size by retrofitting the attachment materials to a raceway pond with a 2000-L capacity and an 8.5 m2 footprint area, as well as a trough reservoir with a 150-L capacity and a 3.5 m2 footprint area. The trough-based RAB system has a maximum productivity of 46.8 g m-2 day-1.

The RAB system shows higher water evaporation loss, the specific water consumption per unit of biomass generated was only 26% (raceway-based RAB) and 7% (trough-based RAB) of that of the control pond. This research demonstrates that the RAB system is an efficient algal culture system with a high potential for commercially producing microalgae with high productivity and efficient water use. (Gross, M., Mascarenhas, V., & Wen, Z. 2015).

Closed System- Photobioreactors (PBRs)

Closed systems or photobioreactors (PBRs) are commonly used in algae cultivation systems due to their numerous advantages over open pond systems. These systems are more efficient in terms of land and water usage and also provide greater control over environmental conditions, such as temperature, light, and nutrient supply. Two common types of closed PBRs are tubular and flat panel systems, but there are various designs and models suggested by many for the cultivation of different microalgae on a mass scale (Znad, H. 2020).

1. Tubular PBRs

Tubular PBRs consist of long, transparent tubes that are either vertically or horizontally oriented. Algae are grown inside the tubes, which are typically made of glass or plastic. The tubes are arranged in a helical or serpentine pattern to increase surface area for light exposure. The tubing can be either continuously or intermittently circulated to promote mixing and prevent stagnation. Researchers generally use tubular PBRs (Photobioreactors) for high-density cultivation and find them well-suited for species that require high light intensity. Controlling the temperature in tubular PBRs is a challenging task, typically accomplished by externally sprinkling deionized water. This sprinkling allows the tubes to cool down, subsequently reducing the temperature of the culture circulating inside them (Torzillo, G., & Chini Zittelli, G. 2015).   

2. Flat panel PBRs

Flat panel PBRs (Photobioreactors) consist of researchers stacking a series of flat, transparent panels on top of each other to create a thin layer of liquid between them. They grow algae in this thin liquid layer while continuously circulating it to promote mixing and prevent stagnation. The panels, typically made of glass or plastic, can be arranged in various configurations to optimize light exposure. Researchers generally use flat panel PBRs for low-to-medium density cultivation and find them well-suited for species that require lower light intensity and maximum surface area for optimal light exposure. They control the temperature in the flat panel PBR system by cooling down the culture in the reservoir chamber using a chilled water jacket and by sprinkling cold water on the flat panel surface (Sierra, E. et al. 2008).

3. Plastic V-Shaped Bag

V-shaped plastic bags are commonly used in closed systems of algae cultivation for several reasons. These bags are made from high-density polyethylene (HDPE) and are designed to hold algae cultures in a closed environment, providing an ideal environment for algae growth. V-shaped plastic bags are effective for growing a variety of algae species, including Chlorella, Spirulina, and Nannochloropsis (Chen, Y. P., et al. 2021).

Chlorella vulgaris exhibited a higher growth rate and biomass yield when cultivated in V-shaped plastic bags compared to other-shaped plastic bags. Different designs of plastic bags based PBR are developed by sealing the plastic bags at different places that generated, flat bottom hanging plastic bags, V-shaped hanging plastic bags, horizontally laying plastic bags that serve the kind of flat PBR system, etc. Many plastics bag-based design is proposed but few are utilized on a commercial scale due to their productivity. The operation of plastic bags is tedious as they need to be replaced after every use to maintain sterility, which is a laborious task for large-scale facilities (Wang, B., et al. 2012, Huang, Q., et al. 2017).

Conclusion:

Algae cultivation technology is becoming an important commercial and economical asset in the algae mass cultivation industry. As the importance of different algal products is growing, their maas cultivation demand makes it necessary to improve and define newer cultivation concepts for significant production. The cultivation methods greatly influence the productivity of particular algae species and eventually, it affects the profit from the cultivation. Therefore, implementing a more economical, operationally feasible, sturdy, easy-to-maintain, and scalable algae cultivation system is becoming a critical aspect of microalgae cultivation practices.

For the growing market of microalgae-based products variety of commercial PBR systems are now coming into the market proving significant progress in this sector. For macroalgae or seaweed, open sea cultivation is becoming a way of the future for their cultivation, and lot many inventions from improving seaweed anchoring, maximum nutrients & CO2 absorption to reimplantation of lost coral reef is happening. Ultimately, the availability of plenty of coastal lines all over the world would play a very essential role in developing new concepts of sea farming of algae.

References:

Borowiak, D., Pstrowska, K., Wiśniewski, M., & Grzebyk, M. (2020). Propagation of Inoculum for Haematococcus pluvialis Microalgae Scale-Up Photobioreactor Cultivation System. Applied Sciences, 10(18), 6283.

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References:

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Gross, M., & Wen, Z. (2014). Yearlong evaluation of performance and durability of a pilot-scale revolving algal biofilm (RAB) cultivation system. Bioresource Technology, 171, 50-58.

Gross, M., Henry, W., Michael, C., & Wen, Z. (2013). Development of a rotating algal biofilm growth system for attached microalgae growth with in situ biomass harvest. Bioresource Technology, 150, 195-201.

Gross, M., Mascarenhas, V., & Wen, Z. (2015). Evaluating algal growth performance and water use efficiency of pilot‐scale revolving algal biofilm (RAB) culture systems. Biotechnology and Bioengineering, 112(10), 2040-2050.

Huang, Q., Jiang, F., Wang, L., & Yang, C. (2017). Design of photobioreactors for mass cultivation of photosynthetic organisms. Engineering, 3(3), 318-329.

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References:

Klein, B., & Davis, R. (2022). Algal Biomass Production via Open Pond Algae Farm Cultivation: 2021 State of Technology and Future Research (No. NREL/TP-5100-82417). National Renewable Energy Lab.(NREL), Golden, CO (United States).

Maltsev, Y., Maltseva, K., Kulikovskiy, M., & Maltseva, S. (2021). Influence of light conditions on microalgae growth and content of lipids, carotenoids, and fatty acid composition. Biology, 10(10), 1060.

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Mehrabadi, A., Craggs, R., & Farid, M. M. (2015). Wastewater treatment high-rate algal ponds (WWT HRAP) for low-cost biofuel production. Bioresource Technology, 184, 202-214.

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Sierra, E. & Acien, Gabriel & Fernández, J. & Garcia, J. & González-López, Cynthia & Molina-Grima, Emilio. (2008). Characterization of a flat plate photobioreactor for the production of microalgae. Chemical Engineering Journal. 138. 136-147. 10.1016/j.cej.2007.06.004.

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Cow Burp and Global Warming – Unexpected but Delicate…

The recent debate on LinkedIn posts by Irina Gerry (Chief Marketing Officer, Change Foods, California, US) about methane production from livestock has started a vigorous discussion. Agri-industrialists, Nutritionists, Naturists, and many others took an active part in it. In one of her posts, she concluded that livestock is a leading contributor to methane and global GHGs. Its current attribute in global warming is about 20-30%. Methane increase global temperature 80 times faster than CO2 in 20 years, or 27 times faster than CO2 in a 100-year run. The UN has targeted 40-45% methane reduction by 2030, and reducing beef consumption is the easiest option according to her. Now, this is surprising that such an invisible natural process could contribute to a serious issue like global warming.

Global annual anthropogenic methane (CH4) emissions (million metric tonnes of carbon dioxide equivalents, MtCO2eq) in 2016 by A) sector, and B) subsectors within the agricultural sector, data sourced from ClimateWatch.

Enteric methane

The enteric fermentation process produced methane in ruminant animals such as cattle, goats, sheep, and buffalos. Ruminants are those that have 4 stomachs, specially designed to digest cellulosic biomass and generate energy. The fibrous biomass after digestion supplies ruminants with necessary proteins, fats, and carbohydrates to generate energy. The microbial consortium present in the stomach digest cellulosic biomass further to produce hydrogen and carbon dioxide. After the utilization of hydrogen by methanogenic bacteria, methane is produced, which is liberated into the environment majorly as cow burps.

Process of Enteric Methane Production

Biogenic carbon cycle

Enteric methane plays important role in nature’s Biogenic Carbon Cycle. When enteric methane is produced, it remains in the environment for 12 years to maintain the atmospheric temperature. During these years, it is oxidized to form CO2 and again enters into the food chain through primary producers. But, due to human interference with the growing population and demand for food and energy, this balance is broken.

Methane produced by one cow is negligible but when produced by billions of cows can impact on a great scale. Currently, it is measured to account for approximately 30% of total global methane emissions. Therefore, curtailing biogenic methane production could be one of the necessary steps to reduce the rapid progression of global warming. Does it mean that livestock farming should be stopped? Or find alternative ways to tackle this issue? Importantly we are at a state where all possible solutions need to be tried at their possible extent of implementation. This may or may not stop climate change but at least will help to bring down GHGs levels. With significant changes in livestock farming, we may be able to reduce the methane footprint of the agriculture sector.

Source: UC Davis, The Biogenic Carbon Cycle and Cattle | CLEAR Center (ucdavis.edu)

Strategies to reduce enteric methane production

Types of feed, nutrient quality, animal health, environmental and geographic conditions, etc. highly influence enteric methane production. When cows are fed with grains as their major diet, they produce more methane than grass-fed cows. The strategies developed to reduce methane production from cow burps include, their diet change or fortification of the diet with additives to improve digestion and reduce methane production, cow breeding to obtain a breed with reduced enteric fermentation, Anti Methanogen Vaccines, Methane-capture wearables, utilization of methane digesters to trap methane produced from cow manure and utilize it as biofuel, etc.

A. Anti-Methanogen Vaccine (Wedlock, D. N. et al. 2013, Baca-González, V. et al. 2020):

The vaccines produced against enteric methanogens trigger antibody production in ruminants. These antibodies bind to methanogens and remove them from the ruminant’s digestive system helping to stop methane production. This concept is still in its early stages of development, but this could prove to be a permanent solution in the near future

B. Methane-capture Wearables (Linzey, C., & Linzey, A. 2021):

In this innovative idea, Zelp’s mask captures methane released directly from the cow’s mouth and flares it. This stops the liberation of enteric methane directly into the atmosphere. This wearable also helps to keep check of ruminants’ health and productivity.

C. Feed modification with additives:

1. 3-Nitrooxypropanol (3-NOP)

3-NOP is a chemical substitute for animal feed that has a similar chemical structure to Methyl-coenzyme M in Archaea. Methyl-coenzyme M reductase (MCR) enzyme plays an essential role in the final step of methane production by binding to methyl-coenzyme M. When 3-NOP is fed to ruminants it replaces methyl-coenzyme M and MCR binding site and stops methane production. In addition to this 3-NOP also oxidizes the Nickel atom present in the core part of the MCR enzyme and disables the whole enzyme from binding to methyl-coenzyme M. This oxidation reaction also produces nitrate, nitrite, and 1,3-propanediol and ultimately degrades 3-NOP in ruminant’s stomach. In general, 40-340mg of 3-NOP/Kg of dry matter intake (DMI) has been used in the research shown to reduce 23-39% methane production in ruminants.

In European Union, commercial 3-NOP manufacturer DSM (Koninklijke DSM N.V. or Royal DSM) patented (WO2012084629A1) their technology to reduce ruminant methane emission, and/or to improve ruminant performance as Bovaer®. With proven trials on large scale, this product has also received clearance from European Food Safety Association (EFSA) in the year 2021.

2. Algae Additives (Glasson C. R. et al. 2022):

With the need to reduce ruminants’ methane emissions, along with a 3-NOP-based solution there are others too coming to the market claiming more efficiency. One of that is Bromoform bioactive compound in extracted form or in whole seaweed-based animal feed that shows almost complete in-vivo methane elimination. A minimum of 1% inclusion level of specific seaweed in feed organic matter (OM) helps to reduce methane from cows and sheep at a significant level. Macroalgae genus Asparagopsis (A. taxiformis and A. armata) has proven to contain such specific inhibitors that reduce methanogenic activity. The key component from algae that contribute to this activity is halogenated methane analogue (HMA) or halomethane. The list of HMA analogue components found in Asparagopsis includes methane, bromochloromethane, dibromochloromethane, chloroform, bromoform, and iodoform. But, the most abundant HMA in Asparagopsis is bromoform.

Mechanism of HMA-

The general reaction carried out by rumen hydrogenotrophic methanogenic archaea involves the conversion of CO2 to Methane through the Wolfe cycle (Thauer, R. K. 2012). 

CO2 + 4H2 → CH4 + 2H2O

Bromoform acts as an anti-methane bioactive compound by blocking the action of key metalloenzymes of the Wolfe cycle. Two essential steps for methane production carried out during the Wolfe cycle are catalyzed by coenzyme M methyltransferase (with a cobalamin prosthetic group) and methyl coenzyme M reductase (MCR) (with nickel tetrapyrrole as a prosthetic group; syn. cofactor F430). Both enzymes are susceptible to competitive and/or oxidative inhibition. The well-discussed mode of action of HMAs in ruminants is competitive binding with coenzyme M methyltransferase and inhibition of methyl transfer in methanogenesis. Whereas halogenated alkanes also block the activity of methyl coenzyme M reductase that catalyzes the final and rate-limiting step of methane production same as explained in the case of 3-NOP.

Drawbacks-

However, the use of HMA bioactive containing seaweed feed for ruminants is always questioned due to their potential carcinogenic and ozone-depleting effects. But it is also discussed by many that both the concerned issues have very negligible impact to consider it as harmful either to human health or leading to the destruction of the ozone layer.

In addition to reducing methane gas production, macroalgae are rich in essential vitamins, minerals, and other nutrients, making them a great addition to any cow’s diet. They are also high in dietary fiber, which helps to prevent digestive disorders and improve the overall health of cows.

Leading Innovators-

Some of the well-known innovators in the sector of seaweed-based feed additives for the reduction of cows’ methane burps are Mootral, Blue Ocean Barns, Symbrosia, Rumin8, Alga Biosciences, Volta Greentech, FutureFeed, CH4 Global, Sea Forest, Greener Grazing, Primary Ocean, The Seaweed Company, Seastock, Seascape Restorations, Agolin.

3. Other Natural ingredients:

Various traditional, as well as newly invented natural solutions for methane reduction in cow burps, include a variety of materials. Many essential oils such as linseed, and extracts that may or may not be scientifically proven have shown applications in methane reduction. This material list includes witchbrew, lemongrass, chestnut, tannins, coconut, garlic extract, cotton oil, wild carrot, coriander seed oil, citrus extracts, ozonated water, green tea and oregano. They are amongst the most effective additives for methane mitigation. Apart from this, adding fats to the cow’s diet offers a promising solution for reducing methanogenesis, without having a significant negative impact on other functions of the rumen.

Methane Reduction from Feed Additives

Conclusion and Future Prospects:

A variety of solutions are available to reduce cow burp and only some of them will prove their potential in near future. In addition, every country’s policy to tackle the issue related to its own carbon footprint is need to be explored. Strong decisions and measures helping toward carbon neutrality need to be pursued.

One example from this category would be the recently flashed news about the New Zealand Government’s implementation of a new tax regime for farmers to reduce greenhouse gas emissions by 10% over the next decade. In this farmers would be taxed for their farm animals as a part of the Government’s commitment to reduce the country’s greenhouse gas emissions to net zero by 2050. The same tax would be expected to raise a high amount of funds that will be made available to support farmers to transition to more sustainable farming practices. Overall, this could potentially set an example for other countries to follow and start investing in better practices to reduce their emissions in the long run. 

Reference:

Wedlock, D. N., Janssen, P. H., Leahy, S. C., Shu, D., & Buddle, B. M. (2013). Progress in the development of vaccines against rumen methanogens. animal, 7, 244-252.

Baca-González, V., Asensio-Calavia, P., González-Acosta, S., Pérez de la Lastra, J. M., & Morales de la Nuez, A. (2020). Are vaccines the solution for methane emissions from ruminants? A systematic review. Vaccines, 8(3), 460.

Linzey, C., & Linzey, A. (2021). Masking the Problem. Journal of Animal Ethics, 11(2), v-vii.

Glasson, C. R., Kinley, R. D., de Nys, R., King, N., Adams, S. L., Packer, M. A., … & Magnusson, M. (2022). Benefits and risks of including the bromoform containing seaweed Asparagopsis in feed for the reduction of methane production from ruminants. Algal Research, 64, 102673.

Thauer, R. K. (2012). The Wolfe cycle comes full circle. Proceedings of the National Academy of Sciences, 109(38), 15084-15085.

Uncategorized

Algae and their Associations- Nature’s unusual and exceptional Secrets

Algae or cyanobacteria are the first atmospheric oxygen producers which also caused a great oxidation event in the era between 2.3 and 2.4 billion years ago. That led to the massive oxidative death of anaerobic bacterial species and even microalgae. Along with changes in the earth’s course around the sun, the atmospheric changes that happened on earth due to an oxidation event contributed to the first Ice Age around 2.3 billion years ago. After the first ice age life on earth started reshaping and gave rise to new eukaryotic cell forms. 

Microalgae being one of the most primitive and photoautotrophic life forms on the earth, evolved and partnered with many other living entities in symbiotic relationships. As a primary producer, they were the food of the first protozoan species that formed the post-first ice age era. Since then, microalgae have formed multiple associations in marine and terrestrial habitats. This article will reveal some of nature’s unusual and exceptional secrets of algae and their associations. Most of these symbiotic relations are examples of the type of commensalism, mutualism, and even parasitism.    

As photo-symbionts (and/or endosymbionts) they form associations with cnidarians, sponges, molluscs, protists (i.e., lichens), and corals, etc. Nitrogen-fixing cyanobacterial species form an association with plants. Some very uncommon relations with microalgae also involve their relationship with vertebrates, which have been revealed in recent years. In this context, we will see some important examples of the symbiotic relationship between algae and other organisms.    

A. Corals (Scleractinia) and Dinoflagellate algae:

Coral reef ecosystems are the best place to observe various associations between different life forms and one of them is Symbiodinium (zooxanthellae). Symbiodinium is the relationship between corals and endosymbiotic Dinoflagellate algae. In order to support coral growth and calcification and provide the necessary nutrients for these diverse and fruitful ecosystems, symbiodinium converts sunlight and carbon dioxide into organic carbon and oxygen. Thus, light has a crucial role in controlling the coral holobiont’s productivity, physiology, and ecology. Symbiodinium has to safely capture sunlight for photosynthesis and expel extra energy to avoid oxidative stress, just like all oxygenic photoautotrophs.

Oxidative stress by environmental stressors like climate change causes coral reefs to bleach and break down coral-algal symbiosis. Large-scale coral bleaching events have increased in frequency and prevalence recently, jeopardizing coral reefs. There is an additional level of diversity in the coral–algal symbiosis because individual corals can host multiple types of Symbiodinium on various temporal and spatial scales.

Image Source: Insights into ‘Symbiodiniaceae phycosphere in a coral holobiont (Garrido, A. G. et al. 2021)

B. Anemones (Anthopleura elegantissima) and Dinoflagellate algae:

Sea anemones typically feed on mussels, shrimp, squid, and other prey. But if this food isn’t available, they obtain sugar from the Dinoflagellates, and Dinoflagellates receive nitrogen, nutrients, shelter, and consistent exposure to sunlight from the host anemone.

Corals and Sea Anemones (Anthozoa) (Image Credit: Smithsonian’s National Zoo & Conservation Biology)

Not all cnidarians that support algae can alter their carbon source. In most cases, such hosts cease to die due to their obligatory association with the symbiont. But in the case of Anthopleura sp. they have heterotrophy with symbionts where they are able to change their nutrient source depending upon the environmental conditions. Which is the same as the case of freshwater hydra. During predatory feeding, hydra manages to reduce the symbiont algal density and during starved conditions, it increases algal density to generate an alternative energy source.

The cost of this symbiotic relationship is that sometimes oxygen stress increased by the symbionts can damage the host cells. Anthopleura sp. can exocytose and egest algal cells to control their densities, but the mechanism behind this phenomenon is not completely understood.

Prediction of algal symbiont contributions based on prey availability (Bedgood, S. A. et al. 2020)

In marine environments as move beyond coral reefs and their attached anemones, we can find host-specific relations between Dinoflagellates and other cnidarians species.

C. Jellyfish (Scyphozoan Cotylorhiza tuberculata) and Dinoflagellates:

Despite the richness of this sort of mutualism, jellyfish and other symbiotic cnidarians remain unexplored. In the 1800 century, scientists found yellow cells inside the tissues of sea animals such as Jellyfish. To this in the year 1882, biologist Sir Patrick Geddes of Edinburgh University proffered a new genus, Philozoon from the Greek phileo, meaning ‘to love as a friend,’ and zoon, meaning ‘animal’, but Philozoon genus name was officially never used. Recently, LaJeunesse et al.2022, supported the postulation made by Sir Patrick Geddes, that the relationship between sea animals and algae was truly symbiotic and not parasitic.

Cotylorhiza tuberculata (Rhizostomae, Scyphozoa) is a Mediterranean jellyfish that hosts an endosymbiotic Dinoflagellate from the Symbiodiniaceae family. In this species, the endosymbiotic relationship begins during the polyp stage of the jellyfish’s early life cycle. Eventually, symbionts are incorporated into their endodermal cells (Via lysosomes), and many of the symbionts containing cells develop into mesogleal amoebocytes. The overpopulated algal cells inside the amoebocytes build up close to the endoderm. Symbiotic Dinoflagellates play a very essential role in the nourishment of jellyfish and spread throughout the gastrovascular system of adult C. tuberculate.

As symbionts play a significant role in jellyfish nutrition, the host may exhibit some behavioral and morphological modifications to keep their photosynthetic partners functioning under optimal lighting conditions. To ensure illumination and maximize photosynthesis, Zooxanthellate jellyfish carry out intricate horizontal and vertical migrations or circadian-regulated tissue contractions. In their medusa stage, Zooxanthellate jellyfish get the majority of their nutritional energy from the symbiont’s photosynthesis. The host gives the symbiont nitrogen and phosphorus in exchange. (Enrique-Navarro, A. et al. 2022).

D. Sponges and Algae:

Many sponges co-evolved with others species, forming obligatory associations with other organisms, ranging from microorganisms to macroalgae. Endosymbiont green algae live close to the surface of some sponges, for example, breadcrumb sponges (Halichondria panicea. The alga is therefore shielded from predators, while the sponge is given oxygen and carbohydrates, which in some species can account for 50 to 80% of sponge growth (Olson, J. B., & Kellogg, C. A. 2010). Many of the macroalgae investigated are found in mesophotic habitats, in association with sponges that include the Halimeda spp., Lobophora variegata, Amphiroa spp., Caulerpa spp., and Dictyota spp. The sponge was also found to be associated with dinoflagellates. It is now known that freshwater sponges can also be found in association with yellow-green algae, cryptophytes, dinoflagellates, and diatoms.

The example of the mutualistic association between the sponge Haliclona caerulea and the calcareous red macroalga Jania adherens is observed on shallow rocky regions of Mazatlán Bay (eastern tropical Pacific, Mexico) (Ávila, E., Carballo, J. L., & Cruz-Barraza, J. A. 2007). In this association, it is found that algae also contribute to the inorganic structure (27%) of the sponge growth specifically under high wave exposure. When experimental studies were carried out on the sponge Haliclona caerulea in association with macroalga Jania adherens, it is observed that in shallow water the wave force impacts greatly the structural properties of the sponge. Here, algal contribution significantly reduces the energy costs of spicule (branches) production in sponges. With increasing depth the increase in the Si: CaCO3 ratio in the sponge structure is observed which implies that the mutualistic relationship between sponge and algae reduces with the depth (Carballo, J. L., et al. 2006).

E. Lichens and Algae:

An association of a fungus (mycobiont) and a photosynthetic (photobiont) resulting in a stable vegetative body having a specific structure is called as a Lichens. It is estimated that around 6-8% of the land surface is covered by lichens with about 20,000 unknown species. In this association, fungi provide water and minerals to the alga, while the algae perform photosynthesis and supply food in the form of sugars to the fungi. Lichens act as pollution indicators as they do not grow in highly polluted environments.

Ascomycota and a few Basidiomycota phylum of kingdom Fungi are found to majorly forms Lichens. As they never occurred separately in nature they might have evolved as a symbiont with one or rarely two species of cyanobacteria as their photobiont. The exception would be a common green alga Trentepohlia is an example that can grow on its own or be lichenized. Lichens also share some specific habitats and even structural morphologies with some algal species (aerophytes) and grow on a tree trunk, rock, etc.

Lichens are miniature ecosystems of fungi, algae, or cyanobacteria which interacts with other microorganisms to evolve as an even more complex composite organism. Due to their long life and slow growth rate they have become an important tool to date the events by lichenometry. The schematic cross-section of foliose lichen explains various parts in its structure (a) the cortex tightly woven out from fungal hyphae (b) photobiont green algae (c) the Medulla with loosely packed hyphae (d) a tightly woven lower cortex (e) Anchoring hyphae called rhizines where the fungus attaches to the substrate.

Image Source: Nefronus – Own work, CC BY-SA 4.0
Example: In India, a Lichen commonly called black stone flower (Parmotrema perlatum) is used as a spice in traditional cuisine. Usually, the dried flowers are tasteless and odorless but heating with oil produces a special earthy fragrance and smoky flavor which enhances the taste of the food.

F. Plants and Algae:

The cyanobacterial in association with other plant species fixes atmospheric nitrogen and makes it available to the host plant. They also provide fixed carbon to the non-photosynthetic host in the form of sugar. The major plant hosts for cyanobacteria are bryophytes, cycads, the angiosperm Gunnera, the water-fern Azolla, and fungi (to form lichens) (Adams, D. G., & Duggan, P. S. 2008).

1. Bryophytes – Nostoc Association

Nostoc spp. by means of its specialized motile filament called hormogonia avails entry into the host system. They can enter into the roots, stems leaves in plants, and thallus of bryophytes such as liverworts and hornworts. After chemoattraction and hormogonia entry of nostoc in the host’s symbiotic cavity, the host inhibits further hormogonia formation. This begins with heterocyst development and dinitrogen fixation. Furthermore, the host suppresses the CO2 fixation rate of the Nostoc and induced more and more dinitrogen fixation for enhanced plant growth (Adams, D. G., & Duggan, P. S. 2008, loc. cit.).

2. Azolla and Anabaena azollae Association Another example of nitrogen-fixing cyanobacterial association with plants is of water fern Azolla’s symbiosis with a cyanobacterium Anabaena azolla. Anabaena colonizes in the base cavities of Azolla fronds. Cyanobacterial heterocyst fixes a sizable amount of nitrogen there. For 1000 years they have been utilized as a source of nitrogen-enriching fertilizers in Southeast Asian wetland paddies. Azolla “blooms” that can fix up to 600 Kg N per hectare per year commonly blanket rice paddies.

G. Hydrozoans:

Another example of Cnidaria is Hydrozoa which are small predatory colonial animals misunderstood as plants and are found in benthic strata (rock and pilings). They have stem pedicles and flower-like heads with mouths and tentacles, the polyps designed for feeding and initial digestion. Some of the polyp colonies are designed for reproduction. The hydrocaulus acts as a root to anchor the colony to the substrate and distribute leftover nutrition to the rest of the colony. Many of the colonies obtain their nutrients from symbiotic algae.

H. Spotted Salamanders and Algae:

The Spotted Salamander (Amblystoma maculatum) species is found across eastern North America. They rise from the soil usually on the first warm and humid night of the spring and travel towards the breeding pool. Females lay a couple or more masses of gelatinous capsules each containing up to 250 fertilized eggs. The egg laid down places are shallow in water and water there contains a very low level of oxygen. And there the secrete of spotted salamander and their symbiont microalgae is concealed.

It is found that egg gelatinous capsules contain green algal growth in them along with the embryo. This algal strain is identified as Chlorococcum amblystomatis, synonym Oophila amblystomatis, commonly known as chlamydomonad algae or salamander algae. This symbiotic algae in the egg capsule produce oxygen with photosynthesis and supply that oxygen to developing embryos. In return, they receive ammonia-rich waste from the embryo to fulfill their nitrogen requirements.

In the year 2010, the assumption that algae reside only in the egg capsule was slacked when researchers found algal cells inside the embryonic cells in early developmental stages. Which is the first of its kind discovery where algae cells are found inhabiting the cells of invertebrates during specific stages of embryo development. The exact mechanism of how and when algae invade embryos is not yet clearly understood.  

Furthermore, in the year 2017, John Burns and colleagues found that a suppressed protein named NF-kappa-b in embryos reduces immunity response. This facilitates the embryos to grow algae inside them (Burns, J. A., et al. 2017).

Conclusion:

The above-given examples suggest that algae can have a symbiotic relationship with smaller unicellular organisms to multicellular vertebrates. And in most relations algae serves as the best partner to nurture its host. In symbiotic relationships, very distinctive partner plays a key role in each other’s survival. From the beginning of life on earth, natural events have been altering the course of species’ development and survival. However, due to anthropogenic changes and environmental pollution by human interventions many such relations are now ceasing to exist. It has also risked and even vanished many of the species and their associations that were not even discovered. However, life’s struggle for sustenance leads to breaching the boundaries and making an ambiguous and unimaginable alliance, and nature keeps evolving the life forms.

References:

Garrido, A. G., Machado, L. F., Zilberberg, C., & Leite, D. C. D. A. (2021). Insights into ‘Symbiodiniaceae phycosphere’in a coral holobiont. Symbiosis, 83(1), 25-39.

Bedgood, S. A., Mastroni, S. E., & Bracken, M. E. (2020). Flexibility of nutritional strategies within a mutualism: food availability affects algal symbiont productivity in two congeneric sea anemone species. Proceedings of the Royal Society B, 287(1940), 20201860.

LaJeunesse, T. C., Wiedenmann, J., Casado-Amezúa, P., D’ambra, I., Turnham, K. E., Nitschke, M. R., … & Suggett, D. J. (2022). Revival of Philozoon Geddes for host-specialized Dinoflagellates,‘zooxanthellae’, in animals from coastal temperate zones of northern and southern hemispheres. European Journal of Phycology, 57(2), 166-180.

Enrique-Navarro, A., Huertas, E., Flander-Putrle, V., Bartual Magro, A., Navarro, G., Ruiz, J., … & Prieto, L. (2022). Living Inside a Jellyfish: The Symbiosis Case Study of Host-Specialized Dinoflagellates,” Zooxanthellae“, and the Scyphozoan Cotylorhiza tuberculata.

Olson, J. B., & Kellogg, C. A. (2010). Microbial ecology of corals, sponges, and algae in mesophotic coral environments. FEMS microbiology ecology, 73(1), 17-30

Carballo, J. L., Avila, E., Enríquez, S., & Camacho, L. (2006). Phenotypic plasticity in a mutualistic association between the sponge Haliclona caerulea and the calcareous macroalga Jania adherens induced by transplanting experiments. I: morphological responses of the sponge. Marine Biology, 148(3), 467-478.

Ávila, E., Carballo, J. L., & Cruz-Barraza, J. A. (2007). Symbiotic relationships between sponges and other organisms from the Sea of Cortes (Mexican Pacific coast): same problems, same solutions. Innovation and Sustainability, 1, 147-156.

Adams, D. G., & Duggan, P. S. (2008). Cyanobacteria–bryophyte symbioses. Journal of experimental botany, 59(5), 1047-1058. Burns, J. A., Zhang, H., Hill, E., Kim, E., & Kerney, R. (2017). Transcriptome analysis illuminates the nature of the intracellular interaction in a vertebrate-algal symbiosis. Elife, 6, e22054.

Clean technology

Algae-based Carbon Capture – A Savior Technology from Global…

Climate change is the long-term shift of weather patterns triggered by changes in atmospheric temperature. Human interference over the last two centuries had accelerated this slow natural process. Which led to increasing atmospheric temperature termed ‘Global Warming‘. To this, the major contributors are increased anthropogenic Carbon dioxide (CO2) and other Greenhouse Gases (GHGs) in the atmosphere. Greenhouse gases are emitted by the combustion of fossil fuels during industrial development and transportation. To stop the climate change scenario, reducing air pollution, controlling CO2 emissions, and environmental Carbon capture are the only solutions.

Naturally, photosynthetic species of microorganisms and plants are major CO2 fixers on the Earth. But, only a natural process won’t be enough and requires positive human intervention. Novel approaches for CO2 scrubbing include chemical and physical techniques of CO2 absorption along with novel membrane-based adsorption technologies. Nevertheless, Ecological solutions also have a potential way out and algae-based carbon capture could be a significant alternative approach. 

What are Greenhouse Gases (GHGs)?

The gases that trap heat energy and increase the atmospheric temperature are called Greenhouse Gases (GHGs). Moreover, different GHGs have a varying capacity for heat entrapment, which is generally referred to as Global Warming Potential (GWP). GWP measures relative heat absorption by 1-ton emission of any GHGs in comparison with 1-ton emission of CO2. CO2, Methane (CH4), and Nitrous oxide (N2O) are major GHG but Fluorinated-gases, especially Hydrofluorocarbons (e.g., chlorofluorocarbons, hydrochlorofluorocarbons, and halons) are high-GWP gases even in the least concentrations.

Source: IPCC (2014)  based on global emissions from 2010. Details about the sources included in these estimates can be found in the Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change

Major CO2 contributors

Industrialization and population growth demanded a forever-increasing need for energy, natural resources, and transportation. This has led to the miss managed exploitation of fossil fuels and natural resources. No doubt, the major industrial sector that contributed to a large amount of CO2 release were energy and transportation. Moreover, manufacturing & construction, agriculture, urbanization and its waste, aviation & shipping, etc. have also contributed to this. Within the last 30 years, CO2 emissions have doubled in the sector of energy to generate electricity and heat. Country-wise, the major CO2-emitting countries are either manufacturers, producers, or consumers of the world’s resources. The countries like China (35.4%), the United States (19%), India (8.9%), Russia (6.3%), and Japan (3.8%) contribute to almost 3/4th of CO2 emissions in comparison with the rest of the world (26.6%).

Source: Hannah Ritchie, Max Roser, and Pablo Rosado (2020) – “CO₂ and Greenhouse Gas Emissions”. Published online at OurWorldInData.org. Retrieved from: ‘https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions’ [Online Resource]
Reference: Net0-Percentage of Carbon Dioxide Emissions by Country

The trend of World CO2 rise in the last 200 Years

In the pre-industrialization era, the atmospheric CO2 was 278ppm which has increased in the last 200 years to 417ppm. Which is almost a 50% increase in the CO2 level from the original. Additionally, in the last 70 years, it has rapidly risen from 5,000 million metric tons to more than 30,000 million metric tons. This significant rise in atmospheric CO2 level has disturbed the Earth’s global temperature balance and led to an increase in the atmospheric temperature almost by 1 degree Celsius (1.8 degrees Fahrenheit). And it is increasing at a rate of more than 0.2 degrees Celsius (0.36 degrees Fahrenheit) per decade.

Source: Global Carbon Dioxide Emissions, 1850–2040 posted by Center for Climate and Energy Solutions, Data Source – Carbon Dioxide Information Analysis Center (Oak Ridge National Laboratory, 2017) & World Energy Outlook (International Energy Agency, 2020).

Global Warming

At a rate of 0.2 degree Celsius per decade, the world’s temperature would attain one degree Celsius more raise in the coming 50 years. This will make a total of 2-degree Celsius increase in the preindustrial era. A sudden increase in temperature will significantly impact Earth’s atmosphere affecting the ocean’s cyclical pattern to volcanic activities. All these changes will lead to devastation on Earth that never happened in human history. Reducing CO2 emission, and capturing to sequester the environmental CO2 are the only viable solutions to reduce the global warming impact.

Ways of CO2 Sequestration and Associated Challenges

With current ongoing applications of fossil fuels and the lack of prominent alternative renewable energy, the release of CO2 will be unavoidable. Keeping CO2 below the level of the specified limit of GHGs to avoid global warming is known as a carbon budget and only that much CO2 release could be permissible. Major fundamental optimizations in industrial operations are required to attain net-zero environmental CO2 release. For CO2 sequestration, Carbon Capture and Utilization (CCU), and Carbon Capture and Storage (CCS) are the two considerable options.

Along with CO2 reduction, CCU offers consumption of CO2 as a raw material for various industrial, research, and commercial prospect and reduce the need of generating new CO2. Under CCS, captured CO2 can be stored under earth-crest-depleted oil and gas reservoirs, and under the oceanic bed, making sure that it will never be released back into the environment. But the risk associated with CCS needs critical evaluation before implementation.

Source: Carbon Sequestration by Wikipedia, Image Title- Schematic showing both terrestrial and geological sequestration of carbon dioxide emissions from heavy industry, such as a chemical plant

Algae show opportunities in both CCU and CCS. Algae sequester and utilize CO2 as a carbon source and store it in the form of algal biomass.

Carbon sequestration by Algae

Oceans are major sinks for global anthropogenic carbon and algae plays a major role in it. Algae photoautotrophically utilizes CO2 and Water in presence of Sunlight to produce Glucose and O2. Photosynthesis reaction has light-dependent and light-independent Phases, both happening inside the chloroplast’s thylakoid and stroma respectively. In the light-dependent phase, light photons donate energy to produce chemical energy ATP and NADPH, using water and releasing O2. This chemical energy (ATP) is utilized in the light-independent phase to produce glucose from CO2.

Image credit: modified from “Overview of photosynthesis: Figure 6” by OpenStax College, Biology, CC BY 3.0

Microalgae can fix > 45 % of the total CO2 and contribute to 40% of total oceanic productivity. They carry massive amounts of organic carbon into the ocean contributing to carbon biological pumps (Reference: Marella et al. 2020, Tréguer et al. 2018). Microalgae production sequesters ~1.8Kg of CO2 /Kg of dried algal biomass. And 2.7 tons/day of CO₂ /Acre. Carbon capture by microalgae is 10 to 50 times higher in amounts than by terrestrial plants. Algae-based CO2 sequestration on an industrial scale has proven to be one of the promising ways to deal with climate change.

Carbon capture by algae in wastewater

Large-scale cultivation of microalgae either in freshwater or marine water with additional nutrients is depending upon their growth requirements and intended final use. Certainly, algae cultivation for CO2 sequestration demands a lot of water. Domestic and industrial wastewater contains lot many contaminants and nutrients that support algal growth. The ratio of C: N: P calculated for wastewater is around 20:8:1 and algae require this ratio at 50:8:1. So, instead of releasing inefficiently treated wastewater into natural water bodies this water could be fortified with additional CO2 and then utilized for algae cultivation along with CO2 sequestration.

Various microalgal species are potential CO2 scavengers and copious growing diatoms are one example. Diatoms basically grow in highly polluted water bodies to neutralize eutrophication. Diatoms fix 20% of the total anthropogenic CO2, which makes them a potential candidate for wastewater bioremediation along with CO2 sequestration.  

Apart from CO2 sequestration potentials, microalgal biomass has many commercial applications including in biofuels and nutritional products.

Limitations of the Algae-based carbon sequestration technology

Light, water, and nutrients are the basic requirement of algae for their growth. Sunlight is available for half day period and using freshwater & pure nutrients for algae cultivation would lead to an unsustainability issue. Facilitating algae cultivation with specialized light sources for nighttime could resolve the issue at an increased cost for light energy, but this will help to keep the process continuous. For fresh water and nutrient sources as mentioned earlier, wastewater could be the potential source and other water resources like marine water can also play an important role.  

Conclusion and future prospects

Algae are the best know environmental agents in carbon capture. Along with their various industrial application, they have proven to create a pavement for the global carbon issue. Finding robust microalgae strains or consortiums for effective CO2 sequestration is the key component in the reduction of GHGs and water pollutants.  Algae biotechnology promises the development of circular economy and biorefinery concepts. Profound research and an effective transition from laboratory studies to industrial scale will be critical steps in this process. Already established comprehensive scientific knowledge on algae-based CO2 sequestration, wastewater treatment, biofuels, and various commercial applications of algae has started taking a shape for sustainable development. And the progress made in this field will definitely lead to carbon neutrality in near future.

Reference

  1. Hannah Ritchie, Max Roser and Pablo Rosado (2020) – “CO₂ and Greenhouse Gas Emissions”. Published online at OurWorldInData.org. Retrieved from: ‘https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions’ [Online Resource]
  2. Marella, T. K., López-Pacheco, I. Y., Parra-Saldívar, R., Dixit, S., & Tiwari, A. (2020). Wealth from waste: Diatoms as tools for phycoremediation of wastewater and for obtaining value from the biomass. Science of the Total Environment, 724, 137960.
  3. Tréguer, P., Bowler, C., Moriceau, B. et al. Influence of diatom diversity on the ocean biological carbon pump. Nature Geosci11, 27–37 (2018). https://doi.org/10.1038/s41561-017-0028-x
Uncategorized

Algae- Potential Revolutionizer Of The World

Water bodies, swamps, slippery footpaths, sewers, etc. all are generally laden with green, slimy growth of algae. Such sites usually remain ignored, and perhaps most of the time algae are eradicated to clean the habitats. Why algae are important? How they evolved? What is their role in nature and why even existed throughout billions of evolutionary years? Many questions are there in curious minds. However, algae had played a significant role in developing the earth’s environment to make it suitable for all living creatures. Nevertheless, they are still doing it.

Algae evolved around 3.5 billion years ago as single-cell autotropic creatures, with the ability to synthesize organic food from inorganic resources. Then it colonized all over the earth and even evolved into the varieties of terrestrial plants we see today. During their colonization, they produced a lot of oxygen that paved the way for the evolution of higher organisms. The oxygen produced was the key component that gave the earth its Ozon layer. Further, it protected all the creatures that evolved after it from lethal sunrays.

What are algae and their types?

Algae originated as a single-cell photosynthetic organism, furthermore evolved to form diverse groups of micro and macro species. Their varieties flourished all over the globe in diversified geographical locations. That includes deep sea, hot water springs, soil, deserted locations, ice glaciers to mountain tops. They thrive in marine as well as freshwater in numerous morphological forms. They are classified as Macroalgae and Microalgae. Macro forms include all the seaweed species that grow very large from a few centimeters to several meters and which are eukaryotic. While microalgae are unicellular or multicellular and prokaryotic as well as eukaryotic. The Department of Botany, Smithsonian National Museum of Natural History, has given the following divisions of algae classifications.

Bacillariophyta (diatoms),

Charophyta (stoneworts),

Chlorophyta (green),

Chrysophyta (golden),

Cyanobacteria (blue-green),

Dinophyta (dinoflagellates),

Phaeophyta (brown),

and Rhodophyta (red),

Credit: Macroalgae Illustration by Fiona Osbaldstone/ Country Life

Human interference in nature’s course

Algae play a major role in sequestering environmental pollutants and maintains the balance in global ecosystems. However, their importance was never recognized until this era of global warming. In the last four centuries, industrialization led to the haphazard utilization of natural resources along with fossil fuels. This liberated tremendous anthropogenic carbon dioxide and greenhouse gases into the environment, which is now a consequence of global warming. The human population failed to limit their desires and never participated significantly to play their role in environmental conservation. Moreover, this has given rise to more complex issues including climate change. Global crises related to freshwater scarcity, food and nutritional security, and breaking the deadliest pandemics are some of those.

Multiple options are put forward to deal with this scenario and comprehensive research is being undertaken to tackle the issues. But, none of it has provided the potential permeant solution. World environmentalists, researchers, public leaders, and economists are working on finding alternative options for sustainable development. Sustainability solutions promise to bring some balance to the above-mentioned world scenario.          

How algae will help?

Algal Exploitation has been made for many centuries for a variety of applications for mankind. Oceans are primary in carbon sequestration and algae play a key role in it. Algae-based CO2 sequestration on an industrial scale has proven to be one of the promising ways to deal with climate change. Apart from this, algae are known for their potential applications in wastewater treatment, food, feed and fodder, biofuels, nutraceuticals, biofertilizers, and pharmaceuticals. This has led to the development of the algal biorefinery concept for biofuel and bio-commodity. Successful implementation of this technology will be a remarkable milestone in the process of overcoming many current global issues. Natural selection always defines the fate of any era. Algae thrived in all, supporting another life form all the way. Hence, algae are nature’s potential key players. Man has an opportunity to sustain and revolutionize his future with the help of algae.

Microalgae Uncategorized

Microalgae – Secret to Strong Immunity by Celebrities

The trend towards microalgae-based foods has been spreading since the last decade. The reason is that such products are loved and promoted by many celebrities worldwide. In 2018, frontiers published a mini-review on “Trends in Microalgae Incorporation Into Innovative Food Products With Potential Health Benefits.” In this report, Martin P. Caporgno and Alexander Mathys discussed the importance of microalgae for food and nutrition security. They also highlighted their potential health benefits.

To discuss from the immunity perspective, understanding the human immune system is essential. Immunity is the inner strength of a person’s body to fight against disease or disease-developing conditions. Scientifically various immunity-specific (inner cellular) and nonspecific (physical) components plan and execute resistance power. They help the biological system recognize, avoid, and fight against a foreign entity. These immunity-specific and nonspecific components are essential to determine how strong is the immune power of that person.

How immunity is developed?

The origin of immunity development determines two basic types of immunities – Innate and Adaptive immunity. Innate immunity – the primary type employed by the genetic makeup and lifestyle of the person. This affects internal and external, specific and nonspecific components. Adaptive immunity – By natural as well as artificial means the person’s body acquires this immunity. This helps to develop more strength in passive or active mode.

The actual physical strength of the person lies in his/her innate immunity, which is the first line of defense. This keeps his/her body strong in all kinds of disease-causing conditions. Good nourishment, good habits, and regular exercise help to develop good innate immunity. Above mentioned components are quite essential for the natural development of the body and to maintain good health. The one component which exerts a major impact on all of them is a healthy and nutritious diet.

Importance of a healthy diet and how microalgae can boost immunity?

One’s diet nourishes with all the nutritional components required for good immunity. Whatever any person eats ultimately plays an important role in developing a good immune system. On average, a person’s whole-day meal contains grains, fruits, meat, dairy products, green leafy vegetables, dry fruits, pulses, etc. This all may provide a sufficient amount of carbs, proteins, fibers and vitamins, minerals, etc. The question is, is it what all require to develop good immunity?

To maintain overall health, the body requires some essential nutritional components. Such components include bioactive, growth factors, essential amino acids, and essential fatty acids. Nutritional health supplements and a special diet provide with necessary additional nutrients. Commercial health supplements add an individual or combination of these nutrients to their formulation. There are essential nutrients in extracts from plants, vegetables, or other natural sources. A regular diet can’t provide these nutrients.

Microalgae

It is possible to obtain many of these essential dietary supplements by consuming whole microalgal biomass. The bioactive compounds present in microalgal biomass promote antioxidative, antihypertensive, immunomodulatory, anticancerogenic, hepato-protective, and anticoagulant activities.

Essential Microalgal Nutrients

Omega-3 polyunsaturated fatty acids (PUFA) such as alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) are known for their importance in the early stages of embryonic and child development, lactating maternal health, and cardiovascular function. Being an integral part of cell membranes, omega -3 fats affect the function of the cell receptors in cell membranes throughout the body tissues. This leads to the cascade reaction of proteins for making hormones that regulate blood clotting, contraction, and relaxation of artery walls, inflammation, and even gene regulation. Fishes are the major source of these components. But in reality, microalgae and phytoplankton are the original sources from where fishes also obtain these nutrients.

Beta Glucan extracted from Euglena gracilis, boosts immunity by training the immunity cells for quick response against pathogens. Natural pigments extracted from microalgae are other essential supplements. They serve as the best source of antioxidant proteins (Like, Astaxanthin, Phycobiliprotein), Chlorophyll, iron, and minerals. These components take part in the direct and indirect improvement of the immune system. Currently marketed microalgae products are Spirulina and Chlorella dried whole biomass powder and tablets as protein and bioactive-rich superfoods. The extracted pure single component also has multiple applications in the food industry and nutraceuticals to improve the human diet. Hence microalgae are explored for various nutritional applications proving that this is going to be the food of the future.

Read More at https://everflowglobal.com/spirulina-powder/: Microalgae – Secret to Strong Immunity by Celebrities
Uncategorized

Spirulina The Future Food For Nutritional Security

Producing enough food for the whole population of the world would be a great task to handle in the coming years. And the pavement through it would be in non-conventional ways, as that of alternative energy sources. In recent years microalgal biomass has received great importance to be an alternative food source. And Spirulina has proven to be the best nutritional supplement even for astronauts.

Spirulina (scientifically known as Arthrospira platensis) is a spiral filamentous microalgal/cyanobacterial species. Its biomass has been utilized as food for many years due to its high protein content. Traditionally known by some African communities as a food source. But, now exploited as the food of the future. It contains vitamins (B, E, and C), proteins, fatty acids, lots of minerals, and some fiber. Furthermore, antioxidants like phycocyanin comprise a major part of its 50-60% protein content. This nutritionally rich nature makes it a complete food. It could provide all the essential nutrients if consumed on a regular basis.

A boon for a healthy life

Changing world climate has an adverse effect on annual food crops and their yield. Hence, having potent alternative food source for the growing society is imperative for food security. Apart from this changing lifestyle, increasing pollution and less nutritive food has reduced our resistance power against diseases. So, the issue of nutritional security is also an important threat to mankind in near future. In such a situation, spirulina can offer an enormous health benefit.

Curative Properties of Spirulina

  • Rich chlorophyll and ion, make it an effective blood-cleansing agent and promotes Hb production.
  • Polysaccharides and pigments boost immunity by increasing the production of WBCs to the desired level.
  • Anti-diabetic and anti-cholesterol components help to fight against diabetes and reduce elevated cholesterol levels.
  • Fibers and minerals help to improve intestinal health by promoting the formation of healthy gut microflora.
  • High protein content helps to reduce fat accumulation and increases muscle strength.
  • Gamma linolenic acid (GLA) improves brain function, skeletal health, and reproductive health. It also stimulates skin and hair growth by improving overall metabolism.
  • Vitamins regulate multiple growth factors in the body and improve physical and mental health.

Production and Socio-economic Impacts

Natural water bodies blooming with spirulina were conventionally the major sources of spirulina biomass. Many biotechnological inventions were made in the last decade to improve production. Laboratory, as well as industrial scale trails, attempted to produce high quality and quantity of biomass. Basic spirulina cultivation systems are raceway ponds that are quite economic to construct as well as to operate. They utilize inorganic chemicals and agricultural fertilizers as a nutrient source for spirulina cultivation.

Various establishments worldwide from smaller to large scale are producing spirulina biomass, but market demand is exponentially increasing every year. In the year 2019, the spirulina global market was $393.6 million. This would reach $897.61 million by 2027, with a CAGR of 10.5% from 2020 to 2027. Widely proven applications of spirulina are in nutraceuticals, food and beverages, cosmetics, and animal feed. It has been implicated with many positive impacts on social as well as economic aspects. Its demand is growing year by year as awareness and importance are spreading.

Due to tremendous potential, spirulina biomass has been recognized as the food of the future by (WHO) and many others. We at Everflow Global believe that spirulina is nature’s marvelous gift to mankind. And therefore, the production of the best quality product is our responsibility. Are you looking to revolutionize your health? Then turn your regular diet with additional benefits of pure and organic spirulina source. Reach out to our experts and let us assist you to understand how spirulina will benefit you.

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