Enhanced photobiological H2 production by the addition of carbon monoxide and hydrogen cyanide in two unicellular N2-fixing cyanobacterial strains isolated from Korean coasts

Photobiological H2 from marine cyanobacterial strains is widely accepted to be an ideal clean and renewable energy source. Using the two Korean N2-fixing unicellular cyanobacterial strains (Cyanothece sp. KNU CB MAL-031 and Cyanothece sp. KNU CB MAL-058) and the Synechococcus sp. Miami strain BG043511 we performed flask-scale experiments to measure the effect of CO and HCN addition on photobiological H2 production. For the test, 1, 5, 10 and 30% v/v of CO in the N2 atmosphere was applied. Enhancement of H2 production was remarkable at 1–5% concentration range of CO addition. At CO concentrations over 5% no further cost-effective enhancement of H2 production was detectable, which suggests to us that 1–5% CO addition should be adopted for practical photobiological H2 production by the cyanobacterial strains. Maximum enhancement of the photobiological H2 production by CO additions was 2–6 times over the control flasks without CO. When 3 ppm of HCN was injected into the cell suspension of BG043511, the enhancement of hydrogen production was 50–60% of that under 5% CO. Present result implies the possible recycling of waste CO and HCN for the enhancement of the photobiological H2 production using marine cyanobacterial strains.