For the past 50 years, microalgae biotechnology has developed a series of applications based on this remarkable group of photosynthetic unicellular organisms. These applications vary from a source for cosmetic products, such as shampoo, ingredients for soap to wash your face or components to put on make-up; for human and animal nutrition through protein-rich feed and dietary supplements, such as Spirulina; it is a source of energy through the creation of biofuels, actively used in bioremediation processes; among others. More importantly, microalgae are responsible for the release, on a global scale, of the most abundant amount of oxygen (O2) into the atmosphere and to capture carbon dioxide (CO2) through photosynthesis.

Microalgae are unicellular organisms that can only be seen through a microscope. They represent an exciting resource for biotechnologists to work with. By many, they are considered tiny cell factories that are ecofriendly and fully sustainable. Most importantly, they grow in a variety of aqueous places: in fresh water, marine systems, in closed lagoons with high salt content and lakes or oases in the middle of deserts.

At Yachay Tech, there are two biotechnologists who focus their efforts on these unicellular organisms; one of them is Professor Spiros Agathos, Dean of the School of Life Sciences and Biotechnology who, along with his Biotechnology Laboratory team at the Catholic University of Louvain (Belgium), works with microalgae collected from extreme environments, such as oases at the Sahara desert, which can tolerate high temperatures in closed areas as well as in high salt content.

With the use of a photobioreactor, the team is subjecting the unusual unicellular microalgae into similar conditions as those in the desert, in search for useful, high added value compounds such as antioxidants that can be introduced in health food supplements. “Our work with microalgae biotechnology is to understand and control the optimal conditions under which these tiny cell factories can optimally produce the compounds”, he says.

There are a wide variety of microalgae species. It has been estimated that there are about 200.000 to 800.000 types of which only 50.000 have been described so far; however, most of them behave in similar ways. Under “stressful conditions”, they accumulate fatty compounds that could be used for the bioproduction of biofuels like biodiesel. “With biotechnological intervention, we think we can manipulate conditions in such way that microalgae can accumulate fuel compounds like lipids or other high value compounds like antioxidants”, Spiros explains. “In fact, we are working in the laboratory to genetically manipulate a type of green algae called Chlamydomonas – a model single-cell green alga – and eventually other less studied but more efficient microalgae, into producing extremely valuable compounds, including biopharmaceuticals by genetic engineering in other parts of the world”. This is one of the reasons there is much excitement about algae and biotechnology these days in the scientific world, because it can potentially be used for sustainable production and at the same time contribute to lowering the CO2 emissions in the world.

“CO2 is a greenhouse gas and microalgae is really well-positioned to capture it”, Spiros explains. “Basically, out of a problematic compound like CO2, we can make something really useful like antioxidant compounds or biofuel, which comes from introducing natural CO2 or, even CO2 from industrial waste gases, in the metabolism of cells”.

Equally important, the large-scale cultivation of microalgae can occur on marginal, non-agricultural land, thus it does not compete with arable land for food production; and it can use wastewater or even seawater, thus it does not consume a progressively scarce resource like fresh water. Finally, the scaled-up cultivation of microalgae can be linked to aquaculture, a strategic sector for Ecuador, since microalgae can both provide feed for aquaculture and serve for the cleanup of waste streams generated from aquaculture.On the other hand, Dr. Si Amar Dahoumane, faculty member of the School of Life Sciences and Biotechnology at Yachay Tech, works with microalgae as a medium for the sustained production of inorganic nanoparticles of gold, silver and gold-silver bimetallic alloys (mixture of a metal and another element). A nanoparticle is a tiny object of 1 to 200 nm in size. “Microalgae are widespread, we have them everywhere. Our research aims at taking advantage of their enzymatic machinery to implement the synthesis of inorganic nanoparticles in an ecofriendly manner”, he explains. “The use of microalgae for the production of noble metal nanoparticles has drawn much attention recently. This is a simple one-step process. The addition of gold cations (an ion with net positive charge having more protons than electrons) into living cultures of microalgae triggers the cells to promote the production of gold nanoparticles (Au-NPs).”

In his research, gold is used as a model metal to investigate the behavior of microalgae and to shed light into the bio-chemical pathways that govern such a biosynthesis process. Through a variety of experiments, Si Amar and colleagues have been able to demonstrate the ability of freshwater microalgae cultures to produce stable ‘solutions’ of Au-NPs, scientifically coined as ‘gold colloids’.

“We feed the culture with the aqueous solutions of gold cations”, Si Amar explains. “These cations (Au3+) are first internalized by the cells and then transformed, through an intracellular mechanism, into their metallic state (Au0). When tens of atoms gather, they form nanoparticles that are released into the culture media. Overall, each cell behaves like a nanobiofactory and the whole culture as a photobioreactor for the creation of gold nanoparticles.”

As it happens naturally, microalgae can adapt to the toxicity of gold and other noble metals by acquiring a resistance and surviving the harsh experimental conditions, allowing these cultures to handle bigger amounts of metal cations and to be reused again and again. This is an important step for biotechnology as it paves the way for the scalability and renewability of such processes. As Si Amar and his team note in a research paper published at Springer Science+Business Media, “the ability of several living organisms to perform the intracellular synthesis of inorganic nanomaterials is not only a fascinating area but also a potential source of applications, especially for the design of cell-based bioreactors”.

The range of gold nanoparticle applications is growing rapidly. These can have a variety of applications in biomedicine for the diagnostics, imaging and hyperthermia treatment of cancer or tumors; in electronics to connect conductors and other elements inside a chip; in sensors that could help identify if foods are suitable for consumption; and in catalysis for chemical reactions. Further progress is needed before designing photobioreactors for nanoparticle production based on microalgae crops. Si Amar’s research is a huge step towards this and has positioned the use of microalgae for metal nanoparticle production in the spotlight.

There are plenty of reasons to think that the possibilities obtained with biotechnology would change the way the world works. Prof. Agathos is confident that the future offers a variety of options for biotechnologists, it is just a matter of time and commitment. “I am excited about being in the position to use at least one platform that is very compatible with sustainable development and long term environmental possibilities that can be environmentally responsible”, he says.

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By: Irene Ycaza – Development Coordination