Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, 310058, China.
Department Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, 04318, Germany.
FEMS Microbiol Ecol. 2022 Apr 21;98(4). doi: 10.1093/femsec/fiac034.
Perchloroethene (PCE) is a widely used chlorinated solvent. PCE is toxic to humans and has been identified as an environmental contaminant at thousands of sites worldwide. Several Dehalococcoides mccartyi strains can transform PCE to ethene, and thus contribute to bioremediation of contaminated sites. Humic acids (HA) are ubiquitous redox-active compounds of natural aquatic and soil systems and have been intensively studied because of their effect in electron transfer. In this study, we observed the dechlorination of PCE was accelerated by HA in mixed cultures containing Dehalococcoides strains. Anthraquinone-2,6-disulfonic acid (AQDS), a humic acid analogue, inhibited PCE dechlorination in our cultures and thus induced an opposite effect on PCE dehalogenation than HA. We observed the same effect on PCE dechlorination with the pure culture of Dehalococcoides mccartyi strain CBDB1. Not only in mixed cultures but also in pure cultures, growth of Dehalococcoides was not influenced by HA but inhibited by AQDS. Enzymatic activity tests confirmed the dehalogenating activity of strain CBDB1 was increased by HA, especially when using hydrogen as electron donor. We conclude that HA enhanced PCE dechlorination by increasing the reaction speed between hydrogen and the dehalogenase enzyme rather than acting as electron shuttle through its quinone moieties.
全氯乙烯（PCE）是一种广泛使用的含氯溶剂。PCE 对人类有毒，已被确定为全球数千个地点的环境污染物。几种 Dehalococcoides mccartyi 菌株可以将 PCE 转化为乙烯，从而有助于受污染地点的生物修复。腐殖酸（HA）是天然水和土壤系统中无处不在的氧化还原活性化合物，由于其在电子转移中的作用，已被深入研究。在这项研究中，我们观察到腐殖酸在含有 Dehalococcoides 菌株的混合培养物中加速了 PCE 的脱氯。蒽醌-2,6-二磺酸（AQDS）是一种腐殖酸类似物，在我们的培养物中抑制了 PCE 的脱氯，因此对 PCE 的脱卤化作用与 HA 相反。我们在 Dehalococcoides mccartyi 菌株 CBDB1 的纯培养物中观察到了对 PCE 脱氯的相同影响。不仅在混合培养物中，而且在纯培养物中，HA 没有影响 Dehalococcoides 的生长，而是被 AQDS 抑制。酶活性测试证实，HA 增加了菌株 CBDB1 的脱卤活性，特别是当使用氢气作为电子供体时。我们得出结论，HA 通过增加氢和脱卤酶之间的反应速度来增强 PCE 的脱氯，而不是通过醌部分作为电子穿梭体起作用。
