Duhamel Melanie, Wehr Stephan D, Yu Lawrence, Rizvi Homa, Seepersad David, Dworatzek Sandra, Cox Evan E, Edwards Elizabeth A
Department of Chemical Engineering and Applied Chemistry, University of Toronto, Ont., Canada.
Water Res. 2002 Oct;36(17):4193-202. doi: 10.1016/s0043-1354(02)00151-3.
An anaerobic mixed microbial culture was enriched from soil and groundwater taken from a site contaminated with trichloroethene (TCE). This enrichment culture was divided into four subcultures amended separately with either perchloroethene (PCE), TCE, cis-dichloroethene (cDCE) or vinyl chloride (VC). In each of the four subcultures, the chlorinated ethenes were rapidly, consistently, and completely converted to ethene at rates of 30-50 micromol/l of culture per day, or an average 160 micro-electron equivalents/l of culture per day. These cultures were capable of sustained and rapid dechlorination of VC, and could not dechlorinate 1,2-dichloroethane, differentiating them from Dehalococcoides ethenogenes, the only known isolate capable of complete dechlorination of PCE to ethene. Chloroform (CF) and 1,1,1-trichloroethane, frequent groundwater co-contaminants with TCE and PCE, inhibited chlorinated ethene dechlorination. Most strongly inhibited was the final conversion of VC to ethene, with complete inhibition occurring at an aqueous CF concentration of 2.5 microM. Differences in rates and community composition developed between the different subcultures, including the loss of the VC enrichment culture's ability to dechlorinate PCE. Denaturing gradient gel electrophoresis of amplified bacterial 16S rRNA gene fragments identified three different DNA sequences in the enrichment cultures, all phylogenetically related to D. ethenogenes. Based on the PCR-DGGE results and substrate utilization patterns, it is apparent that significant mechanistic differences exist between each step of dechlorination from TCE to ethene, especially for the last important dechlorination step from VC to ethene.
从受三氯乙烯（TCE）污染场地采集的土壤和地下水中富集得到一种厌氧混合微生物培养物。将该富集培养物分为四个亚培养物，分别用全氯乙烯（PCE）、TCE、顺式二氯乙烯（cDCE）或氯乙烯（VC）进行修正。在这四个亚培养物中，氯代乙烯均以每天30 - 50微摩尔/升培养物的速率，或平均每天160微电子当量/升培养物的速率迅速、持续且完全地转化为乙烯。这些培养物能够持续且快速地对VC进行脱氯，并且不能对1,2 - 二氯乙烷进行脱氯，这使其与脱卤球菌属产乙烯菌不同，后者是唯一已知的能够将PCE完全脱氯为乙烯的分离菌株。氯仿（CF）和1,1,1 - 三氯乙烷是TCE和PCE常见的地下水共污染物，它们抑制氯代乙烯的脱氯。受抑制最强烈的是VC向乙烯的最终转化，当CF的水溶液浓度为2.5微摩尔时会完全抑制。不同亚培养物之间出现了速率和群落组成的差异，包括VC富集培养物失去了对PCE脱氯的能力。对扩增的细菌16S rRNA基因片段进行变性梯度凝胶电泳，在富集培养物中鉴定出三个不同的DNA序列，它们在系统发育上均与产乙烯脱卤球菌相关。基于PCR - DGGE结果和底物利用模式，从TCE到乙烯的脱氯每个步骤之间显然存在显著的机制差异，尤其是从VC到乙烯的最后一个重要脱氯步骤。
