采集了东南太平洋热液区DY115-20V-S35-TVG17站位的沉积物硫化物样品,其含有76.717％ (m/m)强还原性的磁性良好的黄铁矿.以乳酸钠为电子供体,不溶性的氢氧化铁为电子受体,对该样品进行Fe3+还原细菌的定向富集培养.通过构建该菌群的16S rDNA基因文库,随机挑选82个阳性克隆子进行群落结构多样性分析.研究结果表明:82个克隆代表的6种基因型分别属于4个主要类群,其中ε-变形杆菌占有绝对优势,达到55.2％.此外其还包括厚壁菌门、β-变形杆菌和α-变形杆菌,克隆子比例依次为27.6％、10.3％、6.9％.在富集产物中还原氢氧化铁的功能菌群主要是具有硫还原作用的ε-变形菌中的硫还原菌.%The ocean contains rich resources and in deep sea sediments there exists iron compounds at different stages of oxidation and reduction. Iron is one of the most widely distributed elements on the earth and its cycle chiefly includes two processes of oxidation and reduction. As a primitive form of respiration, Fe3 + -reduction and Fe3 + -reducing bacteria play an important role in the iron cycle where in sediments with an anaerobic environment, where iron chiefly exists in a reduced form. In the current study, a hydrothermal sulfide sample was obtained from the southeast Pacific Ocean, site DY115-20V-S35-TVG17 (50.648 l°N,37.780 2°W, depth 2 783 m) using a television grasp sampler in December, 2008, and was found to be mainly composed of iron pyrite with good magnetism, chiefly Fe1-XS and FeS2, 76.717% (m/m) through X-ray detection. To investigate the diversity of Fe3 +-reducing bacteria in the sample, we designed a medium with sodium lactate as the electron donor and insoluble ferric hydroxide as electron acceptor and cultivated the enriched culture of Fe3 +-reducing bacteria from this sample. The 16S Rdna gene library showed that the 29 selected clones in enriched cultures were clustered into two groups. Pro-teobacteria were the predominant bacterial group which could reach 72.4% , and were mainly distributed into threesubgroups-ε-(55. 2% ) , β- ( 10. 3% ) and α-(6. 9% ) in terms of the percentages of clones. Another commonbacterial group was Firmicutes (27. 6% ). The BLASTn analysis of the clones sequence and phylogenetic tree showed that the functional strains in the enriched cultures responsible for reducing ferric hydroxide were'mainly e-Proteobacteria which could also reduce S0. Our study found that the main group of Fe3 + -reducing bacteria in marine environments was different from that in terrestrial environments. Therefore, we could accelerate our investigation of the compositions of the bacterial communities in different samples by designing special media.
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