Enhanced photo-fermentative hydrogen production from different organic substrate using hupL inactivated Rhodopseudomonas palustris

摘要

Hup hydrogenase in?Rhodopseudomonas palustris?is a type of hydrogen-uptake hydrogenase that mediates hydrogen fixation and utilization. Active Hup hydrogenase is known to inhibit the hydrogen production capacity of?R. palustris. In this study, a Hup hydrogenase inactivated strain,?△hupL CN, was constructed by deleting the hupL gene. Photo hydrogen production was enhanced in the mutant relative to wild-type?R. palustris. The growth characteristics, hydrogen uptake activity and hydrogen production of △hupL CN under different conditions were investigated. Glutamate as nitrogen source and gaseous phase CO2?significantly increased the hydrogen recapture activity of wild bacterium which did not occur in the mutant of △hupL CN as a result of its hydrogen-uptake activity been reduced to a trace level. With glucose, organic acids and dark hydrogen production broth (DHPB) of?Klebsiella oxytoca?HP1 used as substrate, the photo hydrogen production of the mutant was significantly enhanced (from 16.7 to 79.6%) compared with the wild strain. The nitrogen source also exerted a significant effect on the photo hydrogen production of △hupL CN. Glutamate was shown to be a superior nitrogen source for photo hydrogen production of △hupL CN in glucose, but a nitrogen-free environment may be beneficial when acetic acid is used as substrate.