A two-stage, two-organism process for biohydrogen from glucose

H 2 can potentially be produced in a two-stage biological process: the fermentation of glucose by Escherichia coli HD701 and the photofermentation of the residual medium by Rhodobacter sphaeroides O.U. 001. In a typical batch fermentation, E. coli consumed glucose and produced H 2 , organic end-products and biomass. Organic end-products and residual glucose were removed during subsequent photofermentation by R. sphaeroides, with associated growth and neutralization of pH. However, photoproduction of H 2 did not occur during photofermentation of the residual liquor per se due to the presence of fixed nitrogen compounds. Nevertheless, this two-stage approach could be applied to dispose of sugar-containing industrial wastes, H 2 being used for on-site power generation.