Combined 34S, 33S and 18O isotope fractionations record different intracellular steps of microbial sulfate reduction
Combined 34S, 33S and 18O isotope fractionations record different intracellular steps of microbial sulfate reduction
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DOI：
10.1016/j.gca.2017.01.015
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发表时间：
2017-04-15
影响因子：
5
通讯作者：
Bosak, Tanja
中科院分区：
文献类型：
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作者：
Antler, Gilad;Turchyn, Alexandra V.;Bosak, Tanja
微生物硫酸盐还原（MSR）中的几个酶促步骤对细胞外硫酸盐中的S-33/S-32、S-34/S-32和O-18/O-16的同位素比率进行分级，但不同的细胞内过程对残留硫酸盐同位素组成的影响仍然没有很好地量化。我们测量了海洋硫酸盐还原菌 Desulfovibrio sp. 纯培养物中硫酸盐的多种硫 (S-33/S-32、(SS)-S-34-S-/32) 和氧 ((18) O/O-16) 同位素比率。 DMSS-1 生长在不同的有机基质上。这些测量结果与之前报道的氧和硫同位素分馏与细胞特异性 MSR 速率的相关性一致：还原速率越快，所有同位素的同位素分馏就越小。氧和多种硫同位素的组合同位素分馏也与微生物硫酸盐还原过程中的限速步骤和 DsrC 亚基的可用性之间的关系一致。这些实验有助于重建和解释以高 O-18/O-16 和中等 S-34/S-32 比率为特征的天然孔隙水中运行的过程，并表明环境中的一些多同位素信号不能仅用微生物硫酸盐还原来解释。相反，这些信号支持活性但缓慢的硫酸盐还原以及硫化物的再氧化的存在。 (C) 2017 Elsevier Ltd. 保留所有权利。
Several enzymatic steps in microbial sulfate reduction (MSR) fractionate the isotope ratios of S-33/S-32, S-34/S-32 and O-18/O-16 in extracellular sulfate, but the effects of different intracellular processes on the isotopic composition of residual sulfate are still not well quantified. We measured combined multiple sulfur (S-33/S-32, (SS)-S-34-S-/32) and oxygen ((18) O/O-16) isotope ratios of sulfate in pure cultures of a marine sulfate reducing bacterium Desulfovibrio sp. DMSS-1 grown on different organic substrates. These measurements are consistent with the previously reported correlations of oxygen and sulfur isotope fractionations with the cell-specific rate of MSR: faster reduction rates produced smaller isotopic fractionations for all isotopes. Combined isotope fractionation of oxygen and multiple sulfur isotopes are also consistent with the relationship between the rate limiting step during microbial sulfate reduction and the availability of the DsrC subunit. These experiments help reconstruct and interpret processes that operate in natural pore waters characterized by high O-18/O-16 and moderate S-34/S-32 ratios and suggest that some multiple isotope signals in the environment cannot be explained by microbial sulfate reduction alone. Instead, these signals support the presence of active, but slow sulfate reduction as well as the reoxidation of sulfide. (C) 2017 Elsevier Ltd. All rights reserved.