초록
<P><B>Abstract</B></P> <P>Hydrogen yields of dark fermentation are limited due to the need to also produce reduced side products, and photofermentation, an alternative, is limited by the need for light. A relatively new strategy, dark microaerobic fermentation, could potentially overcome both these constraints. Here, application of this strategy demonstrated for the first time significant hydrogen production from lactate by a single organism in the dark. Response surface methodology (RSM) was used to optimize substrate and oxygen concentration as well as inoculum using both (1) regular batch and (2) O<SUB>2</SUB> fed batch cultures. The highest hydrogen yield (HY) was observed under regular batch (1.4±0.1molH<SUB>2</SUB>/mollactate) and the highest hydrogen production (HP) (173.5µmolH<SUB>2</SUB>) was achieved using O<SUB>2</SUB> fed batch. This study has provided proof of principal for the ability of microaerobic fermentation to drive thermodynamically difficult reactions, such as the conversion of lactate to hydrogen.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High hydrogen yield from lactate under dark microaerobic conditions demonstrated. </LI> <LI> Addition of fixed nitrogen had a negative effect on hydrogen production. </LI> <LI> HY was higher using regular batch culture, HP was higher using O<SUB>2</SUB> fed batch. </LI> <LI> Agitation plays an important role in MADF by augmenting oxygen diffusion. </LI> </UL> </P>