Cichocka Danuta, Siegert Michael, Imfeld Gwenaël, Andert Janet, Beck Kirsten, Diekert Gabriele, Richnow Hans-Hermann, Nijenhuis Ivonne
Department of Isotope Biogeochemistry, UFZ-Helmholtz Centre for Environmental Research, Leipzig, Germany.
FEMS Microbiol Ecol. 2007 Oct;62(1):98-107. doi: 10.1111/j.1574-6941.2007.00367.x.
Carbon stable isotope fractionation of tetrachloroethene (PCE) and trichloroethene (TCE) was investigated during reductive dechlorination. Growing cells of Sulfurospirillum multivorans, Sulfurospirillum halorespirans, or Desulfitobacterium sp. strain PCE-S, the respective crude extracts and the abiotic reaction with cyanocobalamin (vitamin B(12)) were used. Fractionation of TCE (alphaC=1.0132-1.0187) by S. multivorans was more than one order of magnitude higher than values previously observed for tetrachloroethene (PCE) (alphaC=1.00042-1.0017). Similar differences in fractionation were observed during reductive dehalogenation by the close relative S. halorespirans with alphaC=1.0046-1.032 and alphaC=1.0187-1.0229 for PCE and TCE respectively. TCE carbon isotope fractionation (alphaC=1.0150) by the purified PCE-reductive dehalogenase from S. multivorans was more than one order of magnitude higher than fractionation of PCE (alphaC=1.0017). Carbon isotope fractionation of TCE by Desulfitobacterium sp. strain PCE-S (alphaC=1.0109-1.0122) as well as during the abiotic reaction with cyanocobalamin (alphaC=1.0154) was in a similar range to previously reported values for fractionation by mixed microbial cultures. In contrast with previous results with PCE, no effects due to rate limitations, uptake or transport of the substrate to the reactive site could be observed during TCE dechlorination. Our results show that prior to a mechanistic interpretation of stable isotope fractionation factors it has to be carefully verified how other factors such as uptake or transport affect the isotope fractionation during degradation experiments with microbial cultures.
在还原脱氯过程中，对四氯乙烯（PCE）和三氯乙烯（TCE）的碳稳定同位素分馏进行了研究。使用了多噬硫螺旋菌、卤代呼吸硫螺旋菌或脱硫脱硫弧菌属菌株PCE - S的生长细胞、各自的粗提物以及与氰钴胺素（维生素B12）的非生物反应。多噬硫螺旋菌对TCE的分馏（αC = 1.0132 - 1.0187）比先前观察到的四氯乙烯（PCE）的值（αC = 1.00042 - 1.0017）高一个多数量级。在密切相关的卤代呼吸硫螺旋菌进行还原脱卤过程中，观察到了类似的分馏差异，PCE和TCE的αC分别为1.0046 - 1.032和1.0187 - 1.0229。多噬硫螺旋菌纯化的PCE - 还原脱卤酶对TCE的碳同位素分馏（αC = 1.0150）比PCE的分馏（αC = 1.0017）高一个多数量级。脱硫脱硫弧菌属菌株PCE - S对TCE的碳同位素分馏（αC = 1.0109 - 1.0122）以及与氰钴胺素的非生物反应过程中的分馏（αC = 1.0154）与先前报道的混合微生物培养物分馏值处于相似范围。与先前PCE的结果相反，在TCE脱氯过程中未观察到由于速率限制、底物向反应位点的摄取或运输而产生的影响。我们的结果表明，在对稳定同位素分馏因子进行机理解释之前，必须仔细验证其他因素（如摄取或运输）如何在微生物培养物降解实验中影响同位素分馏。
