U.S. Geological Survey, Water Resources Division, 432 National Center, Reston, Virginia 22092.
Appl Environ Microbiol. 1988 Jun;54(6):1472-80. doi: 10.1128/aem.54.6.1472-1480.1988.
A dissimilatory Fe(III)- and Mn(IV)-reducing microorganism was isolated from freshwater sediments of the Potomac River, Maryland. The isolate, designated GS-15, grew in defined anaerobic medium with acetate as the sole electron donor and Fe(III), Mn(IV), or nitrate as the sole electron acceptor. GS-15 oxidized acetate to carbon dioxide with the concomitant reduction of amorphic Fe(III) oxide to magnetite (Fe(3)O(4)). When Fe(III) citrate replaced amorphic Fe(III) oxide as the electron acceptor, GS-15 grew faster and reduced all of the added Fe(III) to Fe(II). GS-15 reduced a natural amorphic Fe(III) oxide but did not significantly reduce highly crystalline Fe(III) forms. Fe(III) was reduced optimally at pH 6.7 to 7 and at 30 to 35 degrees C. Ethanol, butyrate, and propionate could also serve as electron donors for Fe(III) reduction. A variety of other organic compounds and hydrogen could not. MnO(2) was completely reduced to Mn(II), which precipitated as rhodochrosite (MnCO(3)). Nitrate was reduced to ammonia. Oxygen could not serve as an electron acceptor, and it inhibited growth with the other electron acceptors. This is the first demonstration that microorganisms can completely oxidize organic compounds with Fe(III) or Mn(IV) as the sole electron acceptor and that oxidation of organic matter coupled to dissimilatory Fe(III) or Mn(IV) reduction can yield energy for microbial growth. GS-15 provides a model for how enzymatically catalyzed reactions can be quantitatively significant mechanisms for the reduction of iron and manganese in anaerobic environments.
从马里兰州波托马克河的淡水沉积物中分离到一种异化的 Fe(III) 和 Mn(IV) 还原微生物。该分离物被命名为 GS-15，可在含有乙酸盐作为唯一电子供体和 Fe(III)、Mn(IV) 或硝酸盐作为唯一电子受体的定义厌氧培养基中生长。GS-15 将乙酸盐氧化为二氧化碳，同时将无定形 Fe(III) 氧化物还原为磁铁矿 (Fe(3)O(4))。当 Fe(III) 柠檬酸盐取代无定形 Fe(III) 氧化物作为电子受体时，GS-15 生长更快，并将所有添加的 Fe(III)还原为 Fe(II)。GS-15 还原天然无定形 Fe(III)氧化物，但不能显著还原高结晶 Fe(III)形式。Fe(III) 在 pH 值为 6.7 至 7 且在 30 至 35 摄氏度时最佳还原。乙醇、丁酸盐和丙酸盐也可以作为 Fe(III) 还原的电子供体。许多其他有机化合物和氢气则不能。MnO(2) 被完全还原为 Mn(II)，Mn(II)沉淀为菱锰矿 (MnCO(3))。硝酸盐被还原为氨。氧气不能作为电子受体，并且它会抑制与其他电子受体的生长。这是首次证明微生物可以完全氧化有机化合物，Fe(III) 或 Mn(IV) 作为唯一电子受体，并且有机物的氧化与异化 Fe(III) 或 Mn(IV) 还原偶联可以为微生物生长提供能量。GS-15 为酶促反应如何成为厌氧环境中 Fe 和 Mn 还原的定量重要机制提供了模型。
