Evaluation of Toluene Degradation Pathways by Two-Dimensional Stable Isotope Fractionation

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• 作者：Carsten Vogt ; Esther Cyrus ; Ilka Herklotz ; Dietmar Schlosser ; Arne Bahr ; Steffi Herrmann ; Hans-Hermann Richnow ; Anko Fischer
• 刊名：Environmental Science & Technology
• 出版年：2008
• 出版时间：November 1, 2008
• 年：2008
• 卷：42
• 期：21
• 页码：7793-7800
• 全文大小：261K
• 年卷期：v.42,no.21(November 1, 2008)
• ISSN：1520-5851

文摘

Toluene degradation by several pure and mixed microbial cultures was investigated by two-dimensional compound specific isotope analysis (2D-CSIA). For most of the cultures, the respective toluene degradation pathway and toluene attacking enzymatic step was known. The slope of the linear regression for hydrogen (Δδ²H) vs carbon (Δδ¹³C) discrimination (Λ = Δδ²H/Δδ¹³C ≈ εH_bulk/εC_bulk) was determined in order to characterize aerobic and anaerobic toluene degradation pathways. The highest Λ value was estimated for the monohydroxylation of the methyl group by Pseudomonas putida (Λ = 53 ± 5). The lowest value was observed for Rhodococcus opacus (Λ = 2 ± 2) due to its insignificant hydrogen fractionation, which indicates that a ring dioxygenase was responsible for the initial attack of toluene. The fungus Cladosprium sphaerospermum containing a cytochrome P450-dependent methyl monooxygenase grouped within these extreme values (Λ = 16 ± 6). Λ values for organisms attacking toluene under anoxic conditions by benzylsuccinate synthase were significantly different and ranged from Λ = 4 ± 3 (Blastochloris sulfoviridis) to 31 ± 11 (strain TRM1). Values were in the same range for organisms using nitrate (Λ = 11−14) or sulfate (Λ = 28−31) as electron acceptor, indicating that it might be possible to distinguish toluene degradation under different electron acceptor conditions by 2D-CSIA.