Woods Angela, Kuntze Kevin, Gelman Faina, Halicz Ludwik, Nijenhuis Ivonne
Department for Isotope Biogeochemistry, Helmholtz Centre for Environmental Research-UFZ, Permoserstrasse 15, D-04318, Leipzig, Germany.
Geological Survey of Israel, 30 Malkhe Israel St., Jerusalem, 95501, Israel.
Chemosphere. 2018 Jan;190:211-217. doi: 10.1016/j.chemosphere.2017.09.128. Epub 2017 Sep 27.
The potential of compound-specific stable isotope analysis (CSIA) to characterize biotransformation of brominated organic compounds (BOCs) was assessed and compared to chlorinated analogues. Sulfurospirillum multivorans and Desulfitobacterium hafniense PCE-S catalyzed the dehalogenation of tribromoethene (TBE) to either vinyl bromide (VB) or ethene, respectively. Significantly lower isotope fractionation was observed for TBE dehalogenation by S. multivorans (ε = -1.3 ± 0.2‰) compared to D. hafniense (ε = -7.7 ± 1.5‰). However, higher fractionation was observed for dibromoethene (DBE) dehalogenation by S. multivorans (ε = -16.8 ± 1.8‰ and -21.2 ± 1.6‰ for trans- and cis-1,2- (DBE) respectively), compared to D. hafniense PCE-S (ε = -9.5 ± 1.2‰ and -14.5 ± 0.7‰ for trans-1,2-DBE and cis-1,2-DBE, respectively). Significant, but similar, bromine fractionation was observed for for S. multivorans (ε = -0.53 ± 0.15‰, -1.03 ± 0.26‰, and -1.18 ± 0.13‰ for trans-1,2-DBE, cis-1,2-DBE and TBE, respectively) and D. hafniense PCE-S (ε = -0.97 ± 0.28‰, -1.16 ± 0.36‰, and -1.34 ± 0.32‰ for cis-1,2-DBE, TBE and trans-1,2-DBE, respectively). Variable CBr dual-element slopes were estimated at Λ (ε/ε) = 1.03 ± 0.2, 17.9 ± 5.8, and 29.9 ± 11.0 for S. multivorans debrominating TBE, cis-1,2-DBE and trans-1,2-DBE, respectively, and at 7.14 ± 1.6, 8.27 ± 3.7, and 8.92 ± 2.4 for D. hafniense PCE-S debrominating trans-1,2-DBE, TBE and cis-1,2-DBE, respectively. A high variability in isotope fractionation, which was substrate property related, was observed for S. multivorans but not D. hafniense, similar as observed for chlorinated ethenes, and may be due to rate-limiting steps preceding the bond-cleavage or differences in the reaction mechanism. Overall, significant isotope fractionation was observed and, therefore, CSIA can be applied to monitor the fate of brominated ethenes in the environment. Isotope effects differences, however, are not systematically comparable to chlorinated ethenes.
评估了化合物特异性稳定同位素分析（CSIA）用于表征溴化有机化合物（BOCs）生物转化的潜力，并与氯化类似物进行了比较。多食硫螺旋菌和哈氏脱硫肠杆菌PCE-S分别催化三溴乙烯（TBE）脱卤生成氯乙烯（VB）或乙烯。与哈氏脱硫肠杆菌（ε = -7.7 ± 1.5‰）相比，多食硫螺旋菌对TBE脱卤的同位素分馏明显更低（ε = -1.3 ± 0.2‰）。然而，与哈氏脱硫肠杆菌PCE-S（反式-1,2-二溴乙烯和顺式-1,2-二溴乙烯（DBE）的ε分别为-9.5 ± 1.2‰和-14.5 ± 0.7‰）相比，多食硫螺旋菌对二溴乙烯（DBE）脱卤的分馏更高（反式和顺式-1,2-二溴乙烯的ε分别为-16.8 ± 1.8‰和-21.2 ± 1.6‰）。观察到多食硫螺旋菌（反式-1,2-二溴乙烯、顺式-1,2-二溴乙烯和TBE的ε分别为-0.53 ± 0.15‰、-1.03 ± 0.26‰和-1.18 ± 0.13‰）和哈氏脱硫肠杆菌PCE-S（顺式-1,2-二溴乙烯、TBE和反式-1,2-二溴乙烯的ε分别为-0.97 ± 0.28‰、-1.16 ± 0.36‰和-1.34 ± 0.32‰）有显著但相似的溴分馏。对于多食硫螺旋菌脱溴TBE、顺式-1,2-二溴乙烯和反式-1,2-二溴乙烯，估计的CBr双元素斜率分别为Λ（ε/ε）= 1.03 ± 0.2、17.9 ± 5.8和29.9 ± 11.；对于哈氏脱硫肠杆菌PCE-S脱溴反式-1,2-二溴乙烯、TBE和顺式-1,2-二溴乙烯，估计的CBr双元素斜率分别为7.14 ± 1.6、8.27 ± 3.7和8.92 ± 2.4。观察到多食硫螺旋菌存在与底物性质相关的同位素分馏高度变异性，但哈氏脱硫肠杆菌没有这种情况，这与氯化乙烯的情况类似，可能是由于键断裂之前的限速步骤或反应机制的差异。总体而言，观察到了显著的同位素分馏，因此CSIA可用于监测环境中溴化乙烯的归宿。然而，同位素效应差异与氯化乙烯没有系统的可比性。
