Effect of cell density and nutrient deprivation on hydrogen production by unicellular green alga Scenedesmus sp. KMITL-OVG1

Abstract

Hydrogen is considered as one of the energy carriers for the near future. H2 production by green algae is catalyzed by hydrogenase activity using electrons from photosynthetic process under the light and from accumulated carbohydrate catabolism in the dark. This research aimed to investigate the effect of cell density and nutrient deprivation on H2 production by Scenedesmus sp. KMITL-OVG1 isolated in Thailand. The result showed that cell culture with the optical density at 750 nm of 0.8 gave the highest H2 production rate. Interestingly, the highest H2 production rate of 1.957 ± 0.100 mL L-1 h-1 and hydrogenase activity of 0.031 ± 0.001 ml L-1 min-1 were found in cells incubated under potassium deprivation. H2 production rate was approximately 3 folds higher than that of cells incubated in normal TAP medium. The increased H2 production rate and hydrogenase activity might be involved in the reduction of starch accumulation. Moreover, the deprivation of potassium combined with other nutrients did not enhance H2 production rate by Scenedesmus sp. KMITL-OVG1.