Benz M, Brune A, Schink B
Fakultat fur Biologie, Universitat Konstanz, Postfach 5560, D-78434 Konstanz, Germany.
Arch Microbiol. 1998 Feb;169(2):159-65. doi: 10.1007/s002030050555.
Nine out of ten anaerobic enrichment cultures inoculated with sediment samples from various freshwater, brackish-water, and marine sediments exhibited ferrous iron oxidation in mineral media with nitrate and an organic cosubstrate at pH 7.2 and 30 degrees C. Anaerobic nitrate-dependent ferrous iron oxidation was a biological process. One strain isolated from brackish-water sediment (strain HidR2, a motile, nonsporeforming, gram-negative rod) was chosen for further investigation of ferrous iron oxidation in the presence of acetate as cosubstrate. Strain HidR2 oxidized between 0.7 and 4.9 mM ferrous iron aerobically and anaerobically at pH 7.2 and 30 degrees C in the presence of small amounts of acetate (between 0.2 and 1.1 mM). The strain gained energy for growth from anaerobic ferrous iron oxidation with nitrate, and the ratio of iron oxidized to acetate provided was constant at limiting acetate supply. The ability to oxidize ferrous iron anaerobically with nitrate at approximately pH 7 appears to be a widespread capacity among mesophilic denitrifying bacteria. Since nitrate-dependent iron oxidation closes the iron cycle within the anoxic zone of sediments and aerobic iron oxidation enhances the reoxidation of ferrous to ferric iron in the oxic zone, both processes increase the importance of iron as a transient electron carrier in the turnover of organic matter in natural sediments.
用来自各种淡水、咸水和海洋沉积物的沉积物样本接种的十分之九的厌氧富集培养物，在pH值为7.2、温度为30摄氏度、含有硝酸盐和有机共底物的矿物培养基中表现出亚铁氧化。厌氧硝酸盐依赖的亚铁氧化是一个生物过程。从咸水沉积物中分离出的一株菌株（菌株HidR2，一种运动的、不形成芽孢的革兰氏阴性杆菌）被选来进一步研究在以乙酸盐作为共底物的情况下亚铁的氧化。在少量乙酸盐（0.2至1.1 mM之间）存在的情况下，菌株HidR2在pH值为7.2、温度为30摄氏度时，有氧和无氧条件下氧化0.7至4.9 mM的亚铁。该菌株通过与硝酸盐进行厌氧亚铁氧化获得生长能量，并且在乙酸盐供应受限的情况下，氧化的铁与提供的乙酸盐的比例保持恒定。在大约pH值为7时，利用硝酸盐厌氧氧化亚铁的能力似乎在嗜温反硝化细菌中广泛存在。由于硝酸盐依赖的铁氧化在沉积物的缺氧区内闭合了铁循环，而有氧铁氧化增强了在有氧区内亚铁向三价铁的再氧化，这两个过程都增加了铁作为天然沉积物中有机物周转过程中的瞬态电子载体的重要性。
