Hydrogen production by Rhodopseudomonas at the expense of vegetable starch, sugarcane juice and whey

Abstract

Four local strains of Rhodopseudomonas sp. (BHU strains 1–4) evolved hydrogen at the expense of potato starch, sugarcane juice and whey (1% in each case) in the presence of light (2 klux), under anaerobic conditions (argon/CO2, 95/5, v/v). Among the three substrates, sugarcane juice supported the maximum level of H2 production, followed by potato starch and whey at the rates of 45, 30 and 25 μl H2 h−1 mg−1 bacterial cell dry weight, respectively. Although elevated temperature (45°C) suppressed H2 evolution by strains 1, 2 and 3, the thermotolerant strain (BHU strain 4) has shown encouraging results. Alginate-immobilized cells under an identical experimental regime, exhibited an almost one-and-a-half times improvement in H2 production in the cases of all the above substrates over their free cell counterpart. Preliminary experiments have shown the presence of amylase in all the bacterial strains and work is in progress to characterize this enzyme so that the system could be used for efficient consumption of starch-based agro- products.