초록
Research on photobiological H<SUB>2</SUB> production processes is pointing towards the use of low cost substrates as sources of reduced carbon for H<SUB>2</SUB> generation. Those substrates (either wastewaters or effluents derived from other fermentation processes) are often rich not only in carbon, but also in fixed nitrogen. NH<SUB>4</SUB><SUP>+</SUP> is an inhibitor of nitrogenase-mediated H<SUB>2</SUB> production in purple non sulfur bacteria. A Rhodopseudomonas palustris mutant strain (NifA*), which constitutively expresses nitrogenase genes, was utilized in order to test the use of NH<SUB>4</SUB><SUP>+</SUP> containing fermentation products for photobiological production of H<SUB>2</SUB>. The strain was grown on both synthetic and waste-derived NH<SUB>4</SUB><SUP>+</SUP> containing media. The nifA* mutant produced H<SUB>2</SUB> in the presence of high concentrations of NH<SUB>4</SUB><SUP>+</SUP>, both in a synthetic medium and in a real vegetable waste-derived medium resulting in higher H<SUB>2</SUB> levels than the wild-type strain. Thus, this study demonstrates that the NifA* strain is well suited to overcome the effects of inhibitory naturally occurring NH<SUB>4</SUB><SUP>+</SUP> as it converts agricultural waste into biofuel.