Xu Shuyun, Fu Bo, Zhang Lijuan, Liu He
Laboratory of Environmental Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, 214122, Jiangsu Province, China.
World J Microbiol Biotechnol. 2015 Jun;31(6):941-50. doi: 10.1007/s11274-015-1848-8. Epub 2015 Apr 3.
Syngas fermentation into ethanol and other bioproducts by mixed cultures is considered a promising biotechnology. Effects of pH on product generation and microbial community during H2/CO2 utilization by acetogen enrichment cultures were investigated in this work. The maximum acetate concentration reached 95.41 mmol L(-1) at pH 7, which was 71.7, 21.8 and 50.9% higher than at pH 5, 9 and 11, respectively. The maximum ethanol concentration at pH 7 was 45.7, 50, 72% higher than that at pH 5, 9 and 11, respectively. The CO dehydrogenase (CODH) gene copy number was highest at pH 7, indicating that metabolically active acetogens reached their highest level at pH 7. The CODH gene copy number at pH 9 was lower than at pH 7, but higher than at pH 5 and 11. Correspondingly, the enrichment cultures at pH 7 had the highest species richness and diversity, while those at pH 9 had the second highest diversity, and those at pH 5 and 11 had the lowest diversity. The shift in microbial community structure and the different active acetogen contents resulting from different pHs were responsible for the differences in acetate and ethanol production.
通过混合培养将合成气发酵为乙醇和其他生物产品被认为是一种很有前景的生物技术。本研究考察了pH值对产乙酸菌富集培养物利用H2/CO2过程中产物生成及微生物群落的影响。在pH 7时，乙酸盐最大浓度达到95.41 mmol L(-1)，分别比pH 5、9和11时高出71.7%、21.8%和50.9%。pH 7时乙醇最大浓度分别比pH 5、9和11时高出45.7%、50%和72%。CO脱氢酶（CODH）基因拷贝数在pH 7时最高，表明代谢活跃的产乙酸菌在pH 7时达到最高水平。pH 9时的CODH基因拷贝数低于pH 7，但高于pH 5和11。相应地，pH 7时的富集培养物具有最高的物种丰富度和多样性，pH 9时的次之，pH 5和11时的最低。不同pH值导致的微生物群落结构变化和活性产乙酸菌含量差异是乙酸盐和乙醇产量不同的原因。
