pH gradient-induced heterogeneity of Fe(III)-reducing microorganisms in coal mining-associated lake sediments
pH gradient-induced heterogeneity of Fe(III)-reducing microorganisms in coal mining-associated lake sediments
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DOI：
10.1128/aem.01194-07
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发表时间：
2008-02-01
影响因子：
4.4
通讯作者：
Kuesel, Kirsten
中科院分区：
文献类型：
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作者：
Bloethe, Marco;Akob, Denise M.;Kuesel, Kirsten
采煤形成的湖泊具有pH低、Fe(II)和硫酸盐浓度高的特点。缺氧沉积物通常分为上酸性带(pH 3；带1)和较深的弱酸性带(pH 5.5；带III)，前者含有大量活性铁，后者含铁量较少。在这项研究中，研究了pH对这两个沉积物带Fe(III)还原活性的影响，并对沉积物微生物多样性进行了分子分析。Fe(II)在I带和III带沉积微宇宙中的形成速率分别约为710和895nmol cm(-3)d(-1)。在pH为5.3的条件下，区带I中Fe(II)的形成增加了2倍。在pH为3的条件下，区带III中Fe(II)的形成受到抑制。克隆文库显示，这两个区带中的大多数克隆(约44%)属于酸杆菌门。由于中等嗜酸性的酸杆菌具有氧化Fe(II)的能力，而由于胶囊酸杆菌在pH值为2到5的范围内还原铁氧化物，这一组似乎参与了铁的循环。与嗜酸杆菌相关的菌种的聚合酶链式反应结果显示，Ⅲ区的嗜酸杆菌或嗜酸杆菌的种系类型数高于区组I。利用地杆菌科特异的引物，在DNA稀释度较高的情况下，从区带III获得了扩增产物。对在pH 5.5条件下生长的Fe(III)还原富集菌克隆文库的系统发育分析表明，大多数克隆与贝塔蛋白细菌成员，主要是硫单胞菌属的成员有密切的亲缘关系。结果表明，在弱酸性条件下，上层酸性沉积物中存在着嗜酸菌或中等嗜酸菌，它们也能还原Fe(III)。弱酸性沉积物中的大多数Fe(III)还原剂在酸性条件下只有很小的活性。
Lakes formed because of coal mining are characterized by low pH and high concentrations of Fe(II) and sulfate. The anoxic sediment is often separated into an upper acidic zone (pH 3; zone 1) with large amounts of reactive iron and a deeper slightly acidic zone (pH 5.5; zone III) with smaller amounts of iron. In this study, the impact of pH on the Fe(III)-reducing activities in both of these sediment zones was investigated, and molecular analyses that elucidated the sediment microbial diversity were performed. Fe(II) was formed in zone I and III sediment microcosms at rates that were approximately 710 and 895 nmol cm(-3) day(-1), respectively. A shift to pH 5.3 conditions increased Fe(II) formation in zone I by a factor of 2. A shift to pH 3 conditions inhibited Fe(II) formation in zone III. Clone libraries revealed that the majority of the clones from both zones (approximately 44%) belonged to the Acidobacteria phylum. Since moderately acidophilic Acidobacteria species have the ability to oxidize Fe(II) and since Acidobacterium capsulatum reduced Fe oxides at pHs ranging from 2 to 5, this group appeared to be involved in the cycling of iron. PCR products specific for species related to Acidiphilium revealed that there were higher numbers of phylotypes related to cultured Acidiphilium or Acidisphaera species in zone III than in zone I. From the PCR products obtained for bioleaching-associated bacteria, only one phylotype with a level of similarity to Acidithiobacillus ferrooxidans of 99% was obtained. Using primer sets specific for Geobacteraceae, PCR products were obtained in higher DNA dilutions from zone III than from zone I. Phylogenetic analysis of clone libraries obtained from Fe(III)-reducing enrichment cultures grown at pH 5.5 revealed that the majority of clones were closely related to members of the Betaproteobacteria, primarily species of Thiomonas. Our results demonstrated that the upper acidic sediment was inhabited by acidophiles or moderate acidophiles which can also reduce Fe(III) under slightly acidic conditions. The majority of Fe(III) reducers inhabiting the slightly acidic sediment had only minor capacities to be active under acidic conditions.