Effects of pH and substrate concentrations on dark fermentative biohydrogen production from xylose by extreme thermophilic mixed culture
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- 作者：Chunsheng Qiu ; Puyu Shi ; Shumin Xiao…
- 关键词：Biohydrogen ; Xylose ; Dark fermentation ; Mixed culture ; Extreme thermophilic
- 刊名：World Journal of Microbiology & Biotechnology
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：33
- 期：1
- 全文大小：673 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Applied Microbiology
Biotechnology
Biochemistry
Environmental Biotechnology
Microbiology - 出版者：Springer Netherlands
- ISSN：1573-0972
- 卷排序：33
文摘
Biohydrogen is considered as one of the most promising energy alternatives considering the climate and energy crisis. The dark fermentative hydrogen production from xylose at extreme thermophilic condition (70 °C) using mixed culture was conducted in this study. The effects of initial pH values (ranged from 5.0 to 10.0) and substrate concentrations (ranged from 2.5 to 15.0 g/L) on the hydrogen production, substrate degradation and metabolite distributions were investigated using batch-mode operations. Results showed that initial substrate pH values in the neutral region (6.0–7.0) were beneficial for hydrogen production. The fermentation at initial pH 7.0 and 7.5 g/L xylose reached an optimal hydrogen yield of 1.29 mol-H2/mol-xyloseconsumed. Ethanol, butyrate, and propionate were the major liquid metabolites. The xylose biodegradation efficiency of the mixed culture decreased sharply at high initial culture pH values. The increase of xylose concentration resulted in the accumulation of propionate and an obvious decrease in the final pH value, as well as a low hydrogen yield. Polymerase chain reaction–denaturing gradient gel electrophoresis analysis indicated that hydrogen producing bacteria were enriched by repeated culture under extreme thermophilic conditions. Also, the mixed culture was dominated with bacterial species related to Clostridium and Thermoanaerobacterium.