Dissimilatory iodate reduction by marine Pseudomonas sp strain SCT
Dissimilatory iodate reduction by marine Pseudomonas sp strain SCT
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DOI：
10.1128/aem.00241-07
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发表时间：
2007-09-01
影响因子：
4.4
通讯作者：
Fujii, Takaaki
中科院分区：
文献类型：
--
作者：
Amachi, Seigo;Kawaguchi, Nahito;Fujii, Takaaki
人们对细菌碘酸盐（IO3-）的还原知之甚少，这主要是由于可用分离株的数量有限以及缺乏有关反应中关键酶的信息。在这项研究中，从海洋沉积物浆中新分离出了一种碘酸盐还原细菌，命名为 SCT 菌株。 SCT 在系统发育上与反硝化细菌施氏假单胞菌密切相关，并在含有 10 mM 硝酸盐的厌氧培养物中在 12 小时内将 200 µLM 碘酸盐还原为碘化物 (I-)。该菌株在有氧条件下不还原碘酸盐。当细胞用 10 mM 硝酸盐和 200 muM 碘酸盐厌氧预生长时，SCT 的厌氧洗涤细胞悬浮液减少了碘酸盐。然而，在没有碘酸盐的情况下预生长的细胞并没有减少它。前一类细胞表现出甲基紫精依赖性碘酸盐还原酶活性（0.31 U mg(-1)），主要位于周质空间。此外，SCT能够以3 mM碘酸盐作为唯一电子受体进行厌氧生长，并且细胞对碘酸盐还原酶(2.46 U mg(-1))表现出增强的活性。这些结果表明SCT是一种异化碘酸盐还原菌，其碘酸盐还原酶是在厌氧生长条件下由碘酸盐诱导的。
Bacterial iodate (IO3-) reduction is poorly understood largely due to the limited number of available isolates as well as the paucity of information about key enzymes involved in the reaction. In this study, an iodatereducing bacterium, designated strain SCT, was newly isolated from marine sediment slurry. SCT is phylogenetically closely related to the denitrifying bacterium Pseudomonas stutzeri and reduced 200 lLM iodate to iodide (I-) within 12 h in an anaerobic culture containing 10 mM nitrate. The strain did not reduce iodate under the aerobic conditions. An anaerobic washed cell suspension of SCT reduced iodate when the cells were pregrown anaerobically with 10 mM nitrate and 200 mu M iodate. However, cells pregrown without iodate did not reduce it. The cells in the former category showed methyl viologen-dependent iodate reductase activity (0.31 U mg(-1)), which was located predominantly in the periplasmic space. Furthermore, SCT was capable of anaerobic growth with 3 mM iodate as the sole electron acceptor, and the cells showed enhanced activity with respect to iodate reductase (2.46 U mg(-1)). These results suggest that SCT is a dissimilatory iodate-reducing bacterium and that its iodate reductase is induced by iodate under anaerobic growth conditions.