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首页> 外文期刊>Applied and Environmental Microbiology >Reduction of Soluble and Insoluble Iron Forms by Membrane Fractions of Shewanella oneidensis Grown under Aerobic and Anaerobic Conditions
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Reduction of Soluble and Insoluble Iron Forms by Membrane Fractions of Shewanella oneidensis Grown under Aerobic and Anaerobic Conditions

机译：有氧和无氧条件下生长的希瓦氏菌的膜分离还原可溶性和不溶性铁的形式

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The effect of iron substrates and growth conditions on in vitro dissimilatory iron reduction by membrane fractions of Shewanella oneidensis MR-1 was characterized. Membrane fractions were separated by sucrose density gradients from cultures grown with O2, fumarate, and aqueous ferric citrate as the terminal electron acceptor. Marker enzyme assays and two-dimensional gel electrophoresis demonstrated the high degree of separation between the outer and cytosolic membrane. Protein expression pattern was similar between chelated iron- and fumarate-grown cultures, but dissimilar for oxygen-grown cultures. Formate-dependent ferric reductase activity was assayed with citrate-Fe3+, ferrozine-Fe3+, and insoluble goethite as electron acceptors. No activity was detected in aerobic cultures. For fumarate and chelated iron-grown cells, the specific activity for the reduction of soluble iron was highest in the cytosolic membrane. The reduction of ferrozine-Fe3+ was greater than the reduction of citrate-Fe3+. With goethite, the specific activity was highest in the total membrane fraction (containing both cytosolic and outer membrane), indicating participation of the outer membrane components in electron flow. Heme protein content and specific activity for iron reduction was highest with chelated iron-grown cultures with no heme proteins in aerobically grown membrane fractions. Western blots showed that CymA, a heme protein involved in iron reduction, expression was also higher in iron-grown cultures compared to fumarate- or aerobic-grown cultures. To study these processes, it is important to use cultures grown with chelated Fe3+ as the electron acceptor and to assay ferric reductase activity using goethite as the substrate.
机译：表征了铁底物和生长条件对Shewanella oneidensis MR-1膜组分体外异化铁还原的影响。膜级分通过蔗糖密度梯度从以O2，富马酸酯和柠檬酸铁水溶液作为末端电子受体生长的培养物中分离。标记酶测定法和二维凝胶电泳显示了外膜和胞质膜之间的高度分离。螯合的铁和富马酸盐生长的培养物之间的蛋白质表达模式相似，而氧生长的培养物则不同。用柠檬酸盐-Fe 3+，亚铁锌-Fe 3+和不溶针铁矿作为电子受体测定了甲酸依赖型铁还原酶的活性。在有氧培养物中未检测到活性。对于富马酸盐和螯合的铁生长细胞，还原可溶性铁的比活性在胞质膜中最高。铁-Fe 3+的还原大于柠檬酸盐-Fe 3+的还原。对于针铁矿，比活性在总膜级分中最高（同时包含胞质和外膜），表明外膜组分参与电子流。螯合的铁生长培养物在需氧生长的膜级分中没有血红素蛋白时，血红素蛋白含量和还原铁的比活最高。 Western印迹显示，与富马酸酯或好氧培养相比，CymAa（一种参与铁还原的血红素蛋白）在铁培养物中的表达也更高。为了研究这些过程，重要的是使用以螯合的Fe3 +作为电子受体生长的培养物，并以针铁矿为底物测定三氧化二铁的活性。

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