Feasibility of biohydrogen production from tofu wastewater with glutamine auxotrophic mutant of Rhodobacter sphaeroides

Abstract

NH 4 +, which is normally the integrant in organic wastewater, such as Tofu wastewater, is an inhibitor to hydrogen production by anoxygenic phototrophic bacterium. In order to release inhibition of NH 4 + to biohydrogen generation by Rhodobacter sphaeroides, a glutamine auxotrophic mutant R. sphaeroides TJ-0803 was obtained by mutagenizing with ethyl methane sulfonate. The mutant could generate biohydrogen efficiently in the medium with high NH 4 + concentration, because the inhibition of NH 4 + to nitrogenase was released. Under suitable conditions, TJ-0803 could effectively produce biohydrogen from tofu wastewater, which commonly containing 50–60 mg L −1 NH 4 +, and the generation rate was increased by more than 100% compared with that from wild-type R. sphaeroides.