Acetate as a carbon source for hydrogen production by photosynthetic bacteria

Hydrogen is a clean energy alternative to fossil fuels. Photosynthetic bacteria produce hydrogen from organic compounds by an anaerobic light-dependent electron transfer process. In the present study hydrogen production by three photosynthetic bacterial strains (Rhodopseudomonas sp., Rhodopseudomonas palustris and a non-identified strain), from four different short-chain organic acids (lactate, malate, acetate and butyrate) was investigated. The effect of light intensity on hydrogen production was also studied by supplying two different light intensities, using acetate as the electron donor. Hydrogen production rates and light efficiencies were compared. Rhodopseudomonas 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 680 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 in acetate concentration from 22 to 11 mM resulted in a decrease in the hydrogen evolved from 214 to 27 ml H-2 per vessel. (C) 2001 Elsevier Science B.V. All rights reserved.