Group of Molecular Microbial Ecology, Institute of Aquatic Ecology (IEA), University of Girona, M a Aurèlia Capmany, 40, E-17003 Girona, Catalonia, Spain.
LEQUIA, Institute of the Environment, University of Girona, M a Aurèlia Capmany, 69, E-17003 Girona, Catalonia, Spain.
FEMS Microbiol Lett. 2018 May 1;365(10). doi: 10.1093/femsle/fny084.
Research efforts aimed at increasing ethanol and butanol productivity from syngas are currently gaining attention. For most model carboxydotrophic bacteria, production rates, yields and maximum product titres have been studied in detail, but little is known on alcohol toxicity in these bacteria. The aim of this work was to investigate the inhibitory effects of ethanol and butanol on the growth of Clostridium ljungdahlii PETC, C. carboxidivorans P7, and 'Butyribacterium methylotrophicum DSM3468'. Experiments to determine inhibitory effects due to product accumulation were carried out using a synthetic mixture of CO:CO2:H2 as a substrate. These conditions were chosen to mimic gaseous effluents of biomass and waste gasification plants. Inhibition effects were recorded as changes in growth parameters. No significant inhibition was observed for ethanol at concentrations below 15 g/L. The three species exhibited higher sensitivity to butanol. Half inhibition constants for butanol could be estimated for P7 (IC50 = 4.12 g/L), DSM3468 (IC50 = 1.79 g/L), and PETC (IC50 = 9.75 g/L). In conclusion, at least for the tested strains, alcohol toxicity is not an immediate handicap for increasing alcohol production of the tested homoacetogenic strains.
目前，人们越来越关注如何提高合成气生产乙醇和丁醇的效率。对于大多数模式产羧菌，其生产速率、产率和最大产物浓度已得到详细研究，但对于这些细菌中醇类的毒性知之甚少。本研究旨在探讨乙醇和丁醇对发酵氢产乙酸菌（Clostridium ljungdahlii PETC）、羧化梭菌（C. carboxidivorans P7）和甲基营养丁酸梭菌（Butyribacterium methylotrophicum DSM3468）生长的抑制作用。采用 CO:CO2:H2 合成混合物作为底物进行了测定产物积累引起的抑制作用的实验。这些条件是为了模拟生物质和废气化厂的气态废气而选择的。抑制作用的记录为生长参数的变化。在浓度低于 15 g/L 的情况下，乙醇没有明显的抑制作用。三种细菌对丁醇的敏感性更高。可以估计出 P7（IC50 = 4.12 g/L）、DSM3468（IC50 = 1.79 g/L）和 PETC（IC50 = 9.75 g/L）的丁醇半抑制常数。总之，至少对于测试的菌株，醇类毒性不会立即成为增加测试同型产乙酸菌酒精产量的障碍。
