Screening cyanobacteria from marine coastal waters of Thailand for biohydrogen production

Abstract

Cyanobacteria are prokaryotic organisms capable of oxygenic photosynthesis. H 2 can be produced by cyanobacterial bidirectional hydrogenase, but mainly during anaerobic dark fermentation. Here, we screened H 2 producing cyanobacteria isolated from marine environments in Thailand and optimized physiological conditions for maximizing H 2 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 H 2 when cells were incubated in nitrogen-deprived medium under dark/anaerobic condition. The filamentous non-heterocystous cyanobacterium Geitlerinema sp. RMK-SH10 gave the highest H 2 yield with highest H 2 production rate found in 7-day grown cells. Geitlerinema sp. RMK-SH10 showed maximum H 2 production rate of 0.271 ± 0.013 μmol H 2 mg −1 dry weight h −1 when incubated in NaNO 3 -free ASN III medium containing 0.2 M NaCl, 18.9 mmol C-atom of glucose L −1 , and 0.1 μM Ni 2+ . These results suggest that the marine filamentous cyanobacterium Geitlerinema sp. RMK-SH10 has high potential as a H 2 producer amenable for further improvement by genetic manipulation.