Acetate as a carbon source for hydrogen production by photosynthetic bacteria

Hydrogen is a clean energy alternative to fossil fuels. Photosynthetic bact eria produce hydrogen from organic compounds by an anaerobic light-dependen t electron transfer process. In the present study hydrogen production by th ree photosynthetic bacterial strains (Rhodopseudomonas sp., Rhodopseudomona s palustris and a non-identified strain), from four different short-chain o rganic acids (lactate, malate, acetate and butyrate) was investigated. The effect of light intensity on hydrogen production was also studied by supply ing two different light intensities, using acetate as the electron donor. H ydrogen production rates and light efficiencies were compared. Rhodopseudom onas sp. produced the highest volume of H-2. This strain reached a maximum H-2 production rate of 25 ml H-2 l(-1) h(-1), under a light intensity of 68 0 mu mol photons m(-2) s(-1), and a maximum light efficiency of 6.2% under a light intensity of 43 pmol photons m(-2) s(-1). Furthermore, a decrease i n acetate concentration from 22 to 11 mM resulted in a decrease in the hydr ogen evolved from 214 to 27 ml H-2 per vessel. (C) 2001 Elsevier Science B. V. All rights reserved.