Treude Nicole, Rosencrantz Dirk, Liesack Werner, Schnell Sylvia
Max-Planck-Institute for terrestrial Microbiology, D-35043 Marburg, Germany.
FEMS Microbiol Ecol. 2003 May 1;44(2):261-9. doi: 10.1016/S0168-6496(03)00048-5.
Dissimilatory iron reduction is of quantitative importance during anaerobic degradation of organic matter in flooded rice field soils. To isolate dissimilatory Fe(III)-reducing microorganisms from rice soil, enrichments were carried out with acetate and ferrihydrite. One of these resulted in the isolation of strain FAc12. This organism grew anaerobically in defined mineral medium with acetate as electron donor and with ferric citrate, ferrihydrite, or nitrate as electron acceptor. Strain FAc12 also grew well aerobically in defined mineral medium with acetate, citrate, glucose, or with complex medium. Comparative sequence analysis of its 16S rRNA gene revealed that strain FAc12 is most closely related to the very recently described Anaeromyxobacter dehalogenans within the order Myxococcales. The overall similarity value between the 16S rRNA gene sequences of strain FAc12 and the type strain of A. dehalogenans (2CP-1) is 99.5%. A. dehalogenans has been reported to be the first facultative anaerobic myxobacterium, while all other members of the Myxococcales were known to be strict aerobes. A. dehalogenans is able to grow by chlororespiration and to utilize nitrate as terminal electron acceptor for growth. Cultivation-independent retrieval of 16S rRNA gene sequences revealed that rice roots are also colonized by various members of this novel subgroup. This information and the metabolic capacity of strain FAc12 allows the assumption that these organisms are physiologically adapted to environments characterized by spatial and temporal fluctuations between oxic and anoxic conditions, as is typically the case for flooded rice soil.
异化铁还原在淹水水稻田土壤中有机物的厌氧降解过程中具有重要的定量意义。为了从水稻土中分离异化铁（III）还原微生物，以乙酸盐和水铁矿进行了富集培养。其中一个培养物导致了菌株FAc12的分离。该微生物在以乙酸盐作为电子供体、柠檬酸铁、水铁矿或硝酸盐作为电子受体的限定矿物培养基中厌氧生长。菌株FAc12在以乙酸盐、柠檬酸盐、葡萄糖为底物的限定矿物培养基或复合培养基中也能很好地有氧生长。对其16S rRNA基因的比较序列分析表明，菌株FAc12与粘球菌目内最近描述的脱卤厌氧粘细菌最为密切相关。菌株FAc12的16S rRNA基因序列与脱卤厌氧粘细菌模式菌株（2CP-1）之间的总体相似性值为99.5%。脱卤厌氧粘细菌被报道为第一个兼性厌氧粘细菌，而粘球菌目的所有其他成员均为严格需氧菌。脱卤厌氧粘细菌能够通过氯呼吸生长，并利用硝酸盐作为生长的末端电子受体。对16S rRNA基因序列进行的非培养检索表明，水稻根也被这个新亚群的各种成员定殖。这些信息以及菌株FAc12的代谢能力表明，这些微生物在生理上适应了以有氧和无氧条件之间的时空波动为特征的环境，淹水水稻土通常就是这种情况。
