Department of Civil Engineering and Engineering Mechanics, University of Arizona, Tucson, Arizona 85721; Department of Environmental Sciences and Engineering, California Institute of Technology, Pasadena, California 91125 ; and Woods Hole Oceanographic Institute, Redfield Laboratory, Woods Hole, Massachusetts 02540.
Appl Environ Microbiol. 1990 Sep;56(9):2811-7. doi: 10.1128/aem.56.9.2811-2817.1990.
Under anaerobic conditions, Shewanella putrefaciens is capable of respiratory-chain-linked, high-rate dissimilatory iron reduction via both a constitutive and inducible Fe(III)-reducing system. In the presence of low levels of dissolved oxygen, however, iron reduction by this microorganism is extremely slow. Fe(II)-trapping experiments in which Fe(III) and O(2) were presented simultaneously to batch cultures of S. putrefaciens indicated that autoxidation of Fe(II) was not responsible for the absence of Fe(III) reduction. Inhibition of cytochrome oxidase with CN resulted in a high rate of Fe(III) reduction in the presence of dissolved O(2), which suggested that respiratory control mechanisms did not involve inhibition of Fe(III) reductase activities or Fe(III) transport by molecular oxygen. Decreasing the intracellular ATP concentrations by using an uncoupler, 2,4-dinitrophenol, did not increase Fe(III) reduction, indicating that the reduction rate was not controlled by the energy status of the cell. Control of electron transport at branch points could account for the observed pattern of respiration in the presence of the competing electron acceptors Fe(III) and O(2).
在厌氧条件下，腐败希瓦氏菌能够通过组成型和诱导型 Fe(III)-还原系统进行呼吸链连接的高速异化铁还原。然而，在低溶解氧水平下，这种微生物的铁还原速度非常缓慢。在将 Fe(III)和 O(2)同时呈现给 S. putrefaciens 分批培养物的 Fe(II)捕获实验中，表明 Fe(II)的自动氧化不是缺乏 Fe(III)还原的原因。用 CN 抑制细胞色素氧化酶会导致在溶解 O(2)存在下 Fe(III)还原的高速率，这表明呼吸控制机制不涉及分子氧抑制 Fe(III)还原酶活性或 Fe(III)运输。使用解偶联剂 2,4-二硝基苯酚降低细胞内 ATP 浓度并没有增加 Fe(III)还原，这表明还原速率不受细胞能量状态的控制。分支点电子传递的控制可以解释在竞争电子受体 Fe(III)和 O(2)存在下观察到的呼吸模式。
