Screening On A Photo-Fermentative Bacterium And Study On The Effect Of Hydrogen Production

The technology of biological hydrogen production, received extensive concerns as its advantages of low costs and being free of pollution. Photo-fermentative bacteria have many special characteristics such as producing hydrogen with sun light, decomposing lots of organic to produce hydrogen without oxygen release. Therefore, photo-fermentative hydrogen production play essential role among biological hydrogen production technology, and screening the strains with high hydrogen producing efficiency has always been the focus of this research field.A photo-fermentative hydrogen-producing bacterium RLD^-119 was isolated from sediment by improved Hungate anaerobic technology. 16S rDNA gene sequence indicated that RLD^-119 was Rhodopseudomonas.sp.RLD^-119 hydrogen production occurred at metaphase and anaphase of the log phase and prophase of the stationary phase. Acetate, malate, lactate, propionate, succinate and glucose were all good carbon source and hydrogen donor for RLD^-119 to produce hydrogen, and butyrate and ethanol could not be used to produce hydrogen, but to grow. In the mixture of acetate and butyrate, it had higher hydrogen producing ability than that of only with acetate when butyrate concentration was lower than 25mM. When the butyrate concentration increased, the hydrogen producing ability was restrained. The glutamate concentration had a significant influence on hydrogen production. The optimum conditions for growth and hydrogen production were 5000 lx-7500 lx, durative light, inoculation with 24h preculture and pH 6.0 - 7.0.In the repeated fed-batch culture, the specific hydrogen production rate increased by adding acetate repeatedly, and RLD^-119 obtained a very high hydrogen production rate of 32.46 ml H₂·g^-1 dry cell·h^-1, and a specific hydrogen production rate of 3.52mol- H2·mol^-1 acetate, 774.43 ml H₂·g^-1 acetate and the substrate conversion efficiency of 88%. Therefore, it is concluded that the repeated fed-batch culture is useful for continuous and stable hydrogen production in high-yield from acetate.Overall, RLD^-119 screened from this research was Rhodopseudomonas.sp and had high efficient hydrogen production. We obtained its optimum conditions for cell growth and hydrogen production which provided efficient figures and laid a cornerstone in the road of engineering application of phototrophic hydrogen production.