Gavrilov S N, Bonch-Osmolovskaia E A, Slobodkin A I
Institute of Microbiology, Russian Academy of Sciences, pr. 60-letya Oktyabrya 7, k. 2, Moscow, 117312 Russia.
Mikrobiologiia. 2003 Mar-Apr;72(2):161-7.
Growth physiology of the iron-reducing bacteria Thermoterrabacterium ferrireducens and Thermoanaerobacter siderophilus was investigated. The stimulation of the organotrophic growth of T. ferrireducens and T. siderophilus in the presence of Fe(III) was shown to be due to the utilization of ferric iron as an electron acceptor in catabolic processes and not to the effect exerted on the metabolism by Fe(II) or by changes in the redox potential. It was established that Fe(III) reduction in T. ferrireducens is not a detoxication strategy. In T. siderophilus, this process is carried out to relieve the inihibitory effect of hydrogen. T. ferrireducens was shown to be capable of lithoautotrophic growth with molecular hydrogen as electron donor and amorphous ferric oxide as electron acceptor, in the absence of any organic substances. The minimum threshold of H2 consumption was 3 x 10(-5) vol % of H2. The presence of CO dehydrogenase activity in T. ferrireducens suggests that CO2 fixation in this organism involves the anaerobic acetyl-CoA pathway. T. siderophilus failed to grow under lithoautotrophic conditions. The fact that T. ferrireducens contains c-type cytochromes and T. sidrophilus lacks them confirms the operation of different mechanisms of ferric iron reduction in these species.
对铁还原菌嗜热陆地杆菌（Thermoterrabacterium ferrireducens）和嗜铁嗜热厌氧菌（Thermoanaerobacter siderophilus）的生长生理学进行了研究。结果表明，在Fe(III)存在的情况下，嗜热陆地杆菌和嗜铁嗜热厌氧菌的有机营养生长受到刺激，这是由于在分解代谢过程中利用三价铁作为电子受体，而不是由于Fe(II)对代谢的影响或氧化还原电位的变化。已确定嗜热陆地杆菌中Fe(III)的还原不是一种解毒策略。在嗜铁嗜热厌氧菌中，进行这个过程是为了减轻氢气的抑制作用。研究表明，嗜热陆地杆菌在没有任何有机物质的情况下，能够以分子氢作为电子供体，无定形氧化铁作为电子受体进行化能自养生长。氢气消耗的最低阈值为H2的3×10(-5)体积%。嗜热陆地杆菌中存在CO脱氢酶活性，这表明该生物体中的CO2固定涉及厌氧乙酰辅酶A途径。嗜铁嗜热厌氧菌在化能自养条件下无法生长。嗜热陆地杆菌含有c型细胞色素而嗜铁嗜热厌氧菌缺乏c型细胞色素这一事实，证实了这些物种中三价铁还原的不同机制的运作。
