Bridge TAM, Johnson DB
School of Biological Sciences, University of Wales, Bangor, LL57 2UW, United Kingdom.
Appl Environ Microbiol. 1998 Jun;64(6):2181-6. doi: 10.1128/AEM.64.6.2181-2186.1998.
Five moderately thermophilic iron-oxidizing bacteria, including representative strains of the three classified species (Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidimicrobium ferrooxidans), were shown to be capable of reducing ferric iron to ferrous iron when they were grown under oxygen limitation conditions. Iron reduction was most readily observed when the isolates were grown as mixotrophs or heterotrophs with glycerol as an electron donor; in addition, some strains were able to couple the oxidation of tetrathionate to the reduction of ferric iron. Cycling of iron between the ferrous and ferric states was observed during batch culture growth in unshaken flasks incubated under aerobic conditions, although the patterns of oxidoreduction of iron varied in different species of iron-oxidizing moderate thermophiles and in strains of a single species (S. acidophilus). All three bacterial species were able to grow anaerobically with ferric iron as a sole electron acceptor; the growth yields correlated with the amount of ferric iron reduced when the isolates were grown in the absence of oxygen. One of the moderate thermophiles (identified as a strain of S. acidophilus) was able to bring about the reductive dissolution of three ferric iron-containing minerals (ferric hydroxide, jarosite, and goethite) when it was grown under restricted aeration conditions with glycerol as a carbon and energy source. The significance of iron reduction by moderately thermophilic iron oxidizers in both environmental and applied contexts is discussed.
五种中度嗜热铁氧化细菌，包括三个已分类物种（嗜热硫化氧化硫杆菌、嗜酸硫化杆菌和氧化亚铁嗜酸菌）的代表性菌株，在氧气受限条件下生长时，被证明能够将三价铁还原为二价铁。当这些分离菌株以甘油作为电子供体进行兼养或异养生长时，最容易观察到铁还原现象；此外，一些菌株能够将连四硫酸盐的氧化与三价铁的还原偶联起来。在有氧条件下培养的未振荡烧瓶中的分批培养生长过程中，观察到了亚铁和三价铁状态之间的铁循环，尽管不同种类的中度嗜热铁氧化细菌以及单一物种（嗜酸硫化杆菌）的菌株中铁的氧化还原模式有所不同。所有这三种细菌物种都能够以三价铁作为唯一电子受体进行厌氧生长；当分离菌株在无氧条件下生长时，生长产量与还原的三价铁量相关。其中一种中度嗜热菌（被鉴定为嗜酸硫化杆菌菌株）在以甘油作为碳源和能源、通气受限的条件下生长时，能够使三种含铁三价矿物（氢氧化铁、黄钾铁矾和针铁矿）发生还原溶解。本文讨论了中度嗜热铁氧化剂在环境和应用背景下铁还原的意义。
