Reyes-Umana Victor, Kretschmer Jessica, Coates John D
Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.
Front Microbiol. 2022 Jan 17;12:804181. doi: 10.3389/fmicb.2021.804181. eCollection 2021.
Recent reports of dissimilatory iodate-reducing microorganisms (DIRM) have arisen from studies of bacteria in marine environments. These studies described the physiology and distribution of DIRM while also demonstrating their presence in iodine-rich marine environments. We posited that despite lower iodine concentrations, terrestrial and freshwater ecosystems should also harbor DIRM. We established numerous enrichments from coastal and freshwater environments that actively remove amended iodate. We describe the physiology and genome of a new DIRM isolate, sp. TC-10, emerging from a freshwater creek microcosm. Like other DIRM, sp. TC-10 couples acetate oxidation to iodate reduction with a concomitant increase in the OD. Our results indicate that sp. TC-10 performs dissimilatory iodate reduction (DIR) using the recently described iodate reductase (Idr). We provide further evidence of horizontal gene transfer of the genes by demonstrating the lack of Idr in the closely related (99.93% 16S rDNA sequence identity) sp. MF63 and describe the heterogeneity of the accessory proteins associated with the iodate reduction island (IRI). These observations provide additional evidence that DIR is a horizontally acquired metabolism with broad environmental distribution beyond exclusively marine environments.
近期关于异化碘酸盐还原微生物（DIRM）的报道源于对海洋环境中细菌的研究。这些研究描述了DIRM的生理学特征和分布情况，同时也证明了它们在富碘海洋环境中的存在。我们推测，尽管陆地和淡水生态系统中的碘浓度较低，但也应该存在DIRM。我们从沿海和淡水环境中建立了大量能够有效去除添加碘酸盐的富集培养物。我们描述了一种新的DIRM分离株——TC-10菌株的生理学特征和基因组，该菌株源自一条淡水小溪的微观生态系统。与其他DIRM一样，TC-10菌株将乙酸氧化与碘酸盐还原耦合，同时伴随着光密度的增加。我们的结果表明，TC-10菌株利用最近描述的碘酸盐还原酶（Idr）进行异化碘酸盐还原（DIR）。通过证明在亲缘关系密切（16S rDNA序列同一性为99.93%）的MF63菌株中缺乏Idr，我们进一步提供了Idr基因水平转移的证据，并描述了与碘酸盐还原岛（IRI）相关的辅助蛋白的异质性。这些观察结果提供了额外的证据，表明DIR是一种通过水平转移获得的代谢方式，其环境分布广泛，不仅仅局限于海洋环境。
