SRINIVAS MUNJAM AND K. JYOTHI RANI
Abstract
Anoxygenic phototrophic bacteria as a part of their photosynthetic metabolism release hydrogen which can be employed as non-conventional and eco-friendly energy source. Rc tenuis KU 017, one such organism isolated from paper industry effluents, was found to produce significant amounts of hydrogen under varied conditions. In the present investigations an effort was made to optimize the conditions for the maximum production of hydrogen by this organism. Actively growing cells were found to be more efficient and sustained hydrogen production for longer period than resting cells. Resting cells preferred light anaerobic conditions for hydrogen production and required more lag period for hydrogen production. Growing cells produced more hydrogen during early phase of growth. The organism was able to utilize a wide variety of organic substances as carbon/electron donors. Sorbitol, formate, lactate and glucose were found to be good sources of carbon for hydrogen production. Growing cells preferred pH 7.0, where as resting cells preferred pH 6.8 with 120h optimum incubation period for hydrogen production. Growing cells produced more hydrogen under aerobic dark than aerobic light conditions. On the other hand, under anaerobic conditions hydrogen production was more in illuminated conditions. Hydrogen production was optimum at temperature range 25-400C. At 300C growing cells produced maximum hydrogen in 120h, while resting cells preferred 96h duration.