Screening cyanobacteria from marine coastal waters of Thailand for biohydrogen production

Abstract

Cyanobacteria are prokaryotic organisms capable of oxygenic photosynthesis. H2 can be produced by cyanobacterial bidirectional hydrogenase, but mainly during anaerobic dark fermentation. Here, we screened H2 producing cyanobacteria isolated from marine environments in Thailand and optimized physiological conditions for maximizing H2 production of the selected isolate. Most of the 54 cyanobacterial strains isolated and purified from samples of seawater, stones, sand, and shells in the Gulf of Thailand and the Andaman Sea, southern part of Thailand produced H2 when cells were incubated in nitrogen-deprived medium under dark/anaerobic condition. The filamentous non-heterocystous cyanobacterium Geitlerinema sp. RMK-SH10 gave the highest H2 yield with highest H2 production rate found in 7-day grown cells. Geitlerinema sp. RMK-SH10 showed maximum H2 production rate of 0.271 ± 0.013 μmol H2 mg−1 dry weight h−1 when incubated in NaNO3-free ASN III medium containing 0.2 M NaCl, 18.9 mmol C-atom of glucose L−1, and 0.1 μM Ni2+. These results suggest that the marine filamentous cyanobacterium Geitlerinema sp. RMK-SH10 has high potential as a H2 producer amenable for further improvement by genetic manipulation.