Sulfur Isotopic Fractionation of Carbonyl Sulfide during Degradation by Soil Bacteria

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• 作者：Kazuki Kamezaki ; Shohei Hattori ; Takahiro Ogawa ; Sakae Toyoda ; Hiromi Kato ; Yoko Katayama ; Naohiro Yoshida
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：April 5, 2016
• 年：2016
• 卷：50
• 期：7
• 页码：3537-3544
• 全文大小：371K
• ISSN：1520-5851

文摘

We performed laboratory incubation experiments on the degradation of gaseous phase carbonyl sulfide (OCS) by soil bacteria to determine its sulfur isotopic fractionation constants (³⁴ε). Incubation experiments were conducted using strains belonging to the genera Mycobacterium, Williamsia, and Cupriavidus isolated from natural soil environments. The ³⁴ε values determined were −3.67 ± 0.33‰, –3.99 ± 0.19‰, –3.57 ± 0.22‰, and −3.56 ± 0.23‰ for Mycobacterium spp. strains THI401, THI402, THI404, and THI405; –3.74 ± 0.29‰ for Williamsia sp. strain THI410; and −2.09 ± 0.07‰ and −2.38 ± 0.35‰ for Cupriavidus spp. strains THI414 and THI415. Although OCS degradation rates divided by cell numbers (cell-specific activity) were different among strains of the same genus, the ³⁴ε values for same genus showed no significant differences. Even though the numbers of bacterial species examined were limited, our results suggest that ³⁴ε values for OCS bacterial degradation depend not on cell-specific activities, but on genus-level biological differences, suggesting that ³⁴ε values are dependent on enzymatic and/or membrane properties. Taking our ³⁴ε values as representative for bacterial OCS degradation, the expected atmospheric changes in δ³⁴S values of OCS range from 0.5‰ to 0.9‰, based on previously reported decreases in OCS concentrations at Mt. Fuji, Japan. Consequently, tropospheric observation of δ³⁴S values for OCS coupled with ³⁴ε values for OCS bacterial degradation can potentially be used to investigate soil as an OCS sink.