Improving hydrogen production using co-cultivation of bacteria with Chlamydomonas reinhardtii microalga

Hydrogen production by microalgae is a promising technology to achieve sustainable and clean energy. Among various photosynthetic microalgae able to produce hydrogen, Chlamydomonas reinhardtii is a model organism widely used to study hydrogen production. Oxygen produced by photosynthesis activity of microalgae has an inhibitory effect on both expression and activity of hydrogenases which are responsible for hydrogen production. Chlamydomonas can reach anoxia and produce hydrogen at low light intensity. Here, the effect of bacteria co-cultivation on hydrogen produced by Chlamydomonas at low light intensity was studied. Results indicated that however co-culturing Escherichia coli, Pseudomonas stutzeri and Pseudomonas putida reduced the growth of Chlamydomonas, it enhanced hydrogen production up to 24 percent, 46 percent and 32 percent, respectively due to higher respiration rate in the bioreactors at low light intensity. Chlamydomonas could grow properly in presence of an unknown bacterial consortium and hydrogen evolution improved up to 56 percent in these co-cultures.