Molecular characterization and hydrogen production of a new species of anaerobe

For the fermentative hydrogen production process with carbohydrates, isolation and identification of hydrogen-producing bacteria (HPB) with high yield and high evolution rate are very important. Improved Hungater rolling tube technique and plate method of culture bottle (PMCB) were used to enumerate and isolate the HPB. The HPB-Li and Ren (HPB-LR) medium was designed to inoculate and isolate HPB under temperature of 37°C and pH of 4.0-6.7. In this study, an isolate of HPB with high yield and high evolution rate was isolated, named Rennanqilyf3 (R3), which is a gram-positive, straight rod, non-spore forming, encapsulated, strict anaerobe, with long peritrichous flagella and three to four metachromatic granules. It performs ethanol-type fermentation, and glucose is its optimum carbon source for hydrogen production. The 16S rDNA sequencing of the R3 isolate indicated that it might be a new species. The hydrogen production capacity of the R3 isolate varied with the glucose concentration and pH. The optimum glucose concentration was 12.0 g/L (with H₂ yield of 58.6 mmolH₂/L-culture) and the optimum initial pH was 5.5 (with H ₂ yield of 34.2 mmolH₂/L-culture). The maximum rate of cell proliferation were 0.46 and 0.63 g/L when glucose concentration was 15.0 g/L and pH was 5.5, respectively. The maximum yields of ethanol and acetic acid were achieved when the glucose concentration was 12.0 g/L and the pH was 5.5.