Departments of Isotope Biogeochemistry and Environmental Microbiology, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany. Isodetect - Company for Isotope Monitoring, Leipzig, Munich, Germany.
Environ Microbiol Rep. 2009 Dec;1(6):535-44. doi: 10.1111/j.1758-2229.2009.00076.x. Epub 2009 Sep 29.
We determined stable carbon and hydrogen isotope fractionation factors for anaerobic degradation of xylene isomers by several pure and mixed cultures. All cultures initiated xylene degradation by the addition of fumarate to a methyl moiety, as is known from the literature or verified by the presence of methylbenzylsuccinates as metabolic intermediates. Additionally, the A subunit of benzylsuccinate synthase (bssA) was identified in the majority of the cultures by bssA-targeted primers. Xylene degradation was always coupled to a significant carbon and hydrogen isotope fractionation. The values of the apparent kinetic isotope effect (AKIE) for carbon and hydrogen indicate that the cleavage of a carbon-hydrogen bond is an isotope-sensitive step during fumarate addition to xylene isomers. The slopes of the linear regression for hydrogen (Δδ(2) H) versus carbon (Δδ(13) C) discrimination (Λ = Δδ(2) H/Δδ(13) C ≈ εHbulk /εCbulk ) ranged from 12 ± 4 to 29 ± 5 and were comparable to Λ values previously determined for anaerobic toluene degradation. The results suggest that combined carbon and hydrogen isotope fractionation analyses can be used to monitor anaerobic xylene degradation at contaminated sites.
我们通过几株纯培养物和混合培养物确定了二甲苯异构体厌氧降解的稳定碳氢同位素分馏因子。所有培养物都是通过向甲基部分添加富马酸盐来启动二甲苯降解的，这是文献中已知的，或者通过存在代谢中间产物甲基苄基琥珀酸酯来验证的。此外，通过苯甲酰琥珀酸合酶（bssA）的靶向引物，在大多数培养物中都鉴定出了 bssA 的 A 亚基。二甲苯降解总是伴随着显著的碳氢同位素分馏。碳和氢的表观动力学同位素效应（AKIE）值表明，在富马酸盐添加到二甲苯异构体时，碳氢键的断裂是一个同位素敏感的步骤。氢（Δδ(2) H）与碳（Δδ(13) C）分馏的线性回归斜率（Λ = Δδ(2) H/Δδ(13) C≈εHbulk /εCbulk）范围为 12±4 到 29±5，与先前确定的厌氧甲苯降解的 Λ 值相当。结果表明，碳氢同位素分馏分析可用于监测污染场地的厌氧二甲苯降解。
