Mao Xinwei, Oremland Ronald S, Liu Tong, Gushgari Sara, Landers Abigail A, Baesman Shaun M, Alvarez-Cohen Lisa
Department of Civil and Environmental Engineering, College of Engineering, University of California , Berkeley, California 94720-1710, United States.
US Geological Survey , Menlo Park, California 94025, United States.
Environ Sci Technol. 2017 Feb 21;51(4):2366-2372. doi: 10.1021/acs.est.6b05770. Epub 2017 Feb 3.
Acetylene (CH) can be generated in contaminated groundwater sites as a consequence of chemical degradation of trichloroethene (TCE) by in situ minerals, and CH is known to inhibit bacterial dechlorination. In this study, we show that while high CH (1.3 mM) concentrations reversibly inhibit reductive dechlorination of TCE by Dehalococcoides mccartyi isolates as well as enrichment cultures containing D. mccartyi sp., low CH (0.4 mM) concentrations do not inhibit growth or metabolism of D. mccartyi. Cocultures of Pelobacter SFB93, a CH-fermenting bacterium, with D. mccartyi strain 195 or with D. mccartyi strain BAV1 were actively sustained by providing acetylene as the electron donor and carbon source while TCE or cis-DCE served as the electron acceptor. Inhibition by acetylene of reductive dechlorination and methanogenesis in the enrichment culture ANAS was observed, and the inhibition was removed by adding Pelobacter SFB93 into the consortium. Transcriptomic analysis of D. mccartyi strain 195 showed genes encoding for reductive dehalogenases (e.g., tceA) were not affected during the CH-inhibition, while genes encoding for ATP synthase, biosynthesis, and Hym hydrogenase were down-regulated during CH inhibition, consistent with the physiological observation of lower cell yields and reduced dechlorination rates in strain 195. These results will help facilitate the optimization of TCE-bioremediation at contaminated sites containing both TCE and CH.
在受污染的地下水场地中，三氯乙烯（TCE）可通过原位矿物进行化学降解从而产生乙炔（CH），并且已知CH会抑制细菌脱氯作用。在本研究中，我们发现，虽然高浓度的CH（1.3 mM）会可逆地抑制麦氏脱卤球菌分离株以及含有麦氏脱卤球菌的富集培养物对TCE的还原脱氯作用，但低浓度的CH（0.4 mM）不会抑制麦氏脱卤球菌的生长或代谢。以乙炔作为电子供体和碳源，同时以TCE或顺式二氯乙烯作为电子受体，可使产CH的发酵细菌佩氏杆菌SFB93与麦氏脱卤球菌菌株195或麦氏脱卤球菌菌株BAV1的共培养物得以有效维持。观察到乙炔对富集培养物ANAS中的还原脱氯作用和产甲烷作用有抑制作用，并且通过向该聚生体中添加佩氏杆菌SFB93可消除这种抑制作用。对麦氏脱卤球菌菌株195的转录组分析表明，在CH抑制过程中，编码还原脱卤酶（如tceA）的基因未受影响，而编码ATP合酶、生物合成和Hym氢化酶的基因在CH抑制过程中表达下调，这与菌株195中较低的细胞产量和降低的脱氯速率的生理学观察结果一致。这些结果将有助于促进在同时含有TCE和CH的受污染场地中对TCE进行生物修复的优化。
