Geomicrobiological Features of Ferruginous Sediments from Lake Towuti, Indonesia.
Geomicrobiological Features of Ferruginous Sediments from Lake Towuti, Indonesia.
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DOI：
10.3389/fmicb.2016.01007
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发表时间：
2016
影响因子：
5.2
通讯作者：
Kallmeyer J
中科院分区：
文献类型：
--
作者：
Vuillemin A;Friese A;Alawi M;Henny C;Nomosatryo S;Wagner D;Crowe SA;Kallmeyer J
Towuti湖是一个构造盆地，被超镁铁质岩石包围。红土通过风化作用形成，并向湖泊及其沉积物提供丰富的铁（氧）氢氧化物，但很少有硫酸盐。为了表征沉积物的地球化学，我们收集了三个网站的核心，增加水深和降低底层水氧浓度。微生物细胞密度是最高的在浅的网站，我们归因于不稳定的有机物（OM）和电子受体的丰度较高，由于好氧的底层水条件的可用性的一个功能。在其他两个网站，OM的降解和还原过程低于氧导致部分电子受体耗尽。遗传信息保存在沉积物中的胞外DNA（eDNA）提供的信息，好氧和厌氧异养相关的硝化螺菌，绿球藻，和热胞浆菌。这些类群显然发挥了重要作用，在下沉OM的降解。然而，eDNA浓度迅速下降的核心深度。尽管硫酸盐浓度很低，硫酸盐还原菌存在，并在所有三个网站的沉积物中的可行性，证实了潜在的硫酸盐还原率的测量。微生物群落指纹图谱支持存在的类群与Deltaproteobacteria和厚壁菌门证明铁和硫酸盐还原能力。同时，瘤胃球菌科、梭菌目和甲烷微生物目的序列表明了发酵产氢和甲烷的潜力。这种对含铁沉积物的首次洞察表明，微生物种群进行与硫，铁和甲烷相关的连续代谢。从理论上讲，铁还原可以再氧化还原态硫化合物，并从铁矿物中解吸OM，使其再矿化为甲烷。总的来说，我们发现，沉积物中的地球化学过程可以链接到氧化还原差异的底部沃茨的三个网站，如氧化剂浓度和供应不稳定的OM。在湖泊记录的尺度上，我们的地质微生物学研究应该提供一种手段，将现存的地下生物圈与过去的环境联系起来。
Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site—a feature we attribute to the availability of labile organic matter (OM) and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA (eDNA) provided information on aerobic and anaerobic heterotrophs related to Nitrospirae, Chloroflexi, and Thermoplasmatales. These taxa apparently played a significant role in the degradation of sinking OM. However, eDNA concentrations rapidly decreased with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales, and Methanomicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments showed that microbial populations perform successive metabolisms related to sulfur, iron, and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant concentrations and the supply of labile OM. At the scale of the lacustrine record, our geomicrobiological study should provide a means to link the extant subsurface biosphere to past environments.