Cyanobacteria are ubiquitous prokaryotic microorganisms. They are so versatile in nature that these extraordinary microbes have evolved to be adaptable to extreme environmental conditions ranging from the arid regions of Antarctica to the dry plains of Atacama Desert.
For decades, scientists around the world have been investigating the secret lives of these microbes, looking to unravel their nature. Being capable of photosynthesis makes them almost self-sufficient and capable of flourishing rapidly in the presence of minimum nutrients in the environment. Some strains of cyanobacteria are also capable of fixing atmospheric nitrogen through the use of specialized cells called heterocyst. Under nitrogen deprived conditions, heterocysts can aid in the production of hydrogen gas as a byproduct with the help of specific enzymes called nitrogenases. The cyanobacterial biomass can further be processed to biodiesel and other biofuel products such as bioethanol, etc.
These properties of cyanobacteria make them a promising host for designing efficient biofuel production systems.
Biohydrogen is an excellent example of clean source of energy which leaves behind minimum carbon foot prints. It is notable that hydrogen fuel cell vehicles produce zero emission, emitting only water as waste on combustion. Application of this technology is not very far-fetched with the current developments in engineering. Automobile companies such as BMW and Honda already have vehicles in the market that are capable of directly utilizing hydrogen gas for energy.
By using thin films the surface area is increased enabling better light utilization and gas diffusion. There is also significant reduction in self-shading by cells, which is a common problem in the ponds. So far we have achieved a maximum light utilization efficiency of 2% with our current knowledge.
Our research on artificial biofilms demonstrate that this technology could be employed in the future for mass production of biohydrogen, but much more research efforts are still needed for this product to reach industrial scale. In order to make the production rates industrially feasible, we are aiming towards reaching an efficiency level of about 10%.
My research is primarily focused on the optimization of these artificial cyanobacterial biofilms for improving maximum solar light utilization and efficient reduction of CO2 mainly from the industrial pollutants through the natural process of photosynthesis. This technology also has alternative environmental friendly applications such as for increasing the efficiency of water purification systems (e.g. removing excess ammonia) that rely on photosynthetic microorganisms.
These biofilms with entrapped cyanobacteria have not only the capacity to produce renewable energy in the form of biohydrogen but also some industrially valuable compounds, such as pigments and antioxidants; this aspect is also investigated in my work.
Gayathri Murukesan
gamuru(at)utu.fi
The writer is working as a researcher in “Bioenergy from Cyanobacteria and Microalgae Group”, University of Turku. The PhD project “Engineering of a High Efficient Solar-Driven Hydrogen-Producing System for Long-Term Hydrogen Production and CO2 sequestration” is funded by Nessling Foundation.
