Predominance of Viable Spore-Forming Piezophilic Bacteria in High-Pressure Enrichment Cultures from ~1.5 to 2.4 km-Deep Coal-Bearing Sediments below the Ocean Floor.
Predominance of Viable Spore-Forming Piezophilic Bacteria in High-Pressure Enrichment Cultures from ~1.5 to 2.4 km-Deep Coal-Bearing Sediments below the Ocean Floor.
复制标题
海底以下 1.5 至 2.4 公里深含煤沉积物的高压富集培养物中存活孢子形成的嗜压细菌的优势
DOI：
10.3389/fmicb.2017.00137
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发表时间：
2017
影响因子：
5.2
通讯作者：
Inagaki F
中科院分区：
文献类型：
--
作者：
Fang J;Kato C;Runko GM;Nogi Y;Hori T;Li J;Morono Y;Inagaki F
在海底以下约2.5公里的海洋地下沉积物中观察到了系统发育多样性的微生物(Kmbsf)。然而，尽管压力直接影响微生物的生理、新陈代谢以及就地碳和其他元素的生物地球化学过程，但对海底深层生物圈中适应压力和/或喜爱压力的微生物，即所谓的压力菌，知之甚少。在这项研究中，我们研究了在日本岛下半岛外的综合海洋钻探计划(IODP)考察337期间获得的高压孵化沉积物中微生物群落的分类组成。对16S rRNA基因标记序列的分析表明，在约1.5~2.4 km深度的沉积物样品中，所有富集培养物中都主要检测到菲尔米库特和放线杆菌中的芽胞形成菌，其次是变形杆菌、酸性细菌和拟杆菌。为了进一步研究深海海底沉积物中嗜压细菌的生理特性，我们分别从1.9和2.4 km深的沉积物样品中分离并鉴定了两株细菌19R1-5和29R7-12。分离到的菌株均为低G+C含量、革兰氏阳性、内孢子形成和兼性厌氧嗜压菌，分别与泛球杆菌和枯草芽孢杆菌亲缘关系较近。菌株19R1-5的最适生长压力和温度分别为20 Mpa和42℃，菌株29R7-12的最适生长压力和生长温度分别为10 Mpa和43℃。细菌(Endo)孢子在富集物和纯培养物中都被观察到，这表明这些嗜压菌群是在作为孢子长期存活后埋藏在约2000万年含煤沉积物中的微生物群落中产生的，生物圈深层可能拥有比迄今所认识的更丰富的革兰氏阳性芽胞形成细菌及其孢子。
Phylogenetically diverse microorganisms have been observed in marine subsurface sediments down to ~2.5 km below the seafloor (kmbsf). However, very little is known about the pressure-adapted and/or pressure-loving microorganisms, the so called piezophiles, in the deep subseafloor biosphere, despite that pressure directly affects microbial physiology, metabolism, and biogeochemical processes of carbon and other elements in situ. In this study, we studied taxonomic compositions of microbial communities in high-pressure incubated sediment, obtained during the Integrated Ocean Drilling Program (IODP) Expedition 337 off the Shimokita Peninsula, Japan. Analysis of 16S rRNA gene-tagged sequences showed that members of spore-forming bacteria within Firmicutes and Actinobacteria were predominantly detected in all enrichment cultures from ~1.5 to 2.4 km-deep sediment samples, followed by members of Proteobacteria, Acidobacteria, and Bacteroidetes according to the sequence frequency. To further study the physiology of the deep subseafloor sedimentary piezophilic bacteria, we isolated and characterized two bacterial strains, 19R1-5 and 29R7-12, from 1.9 and 2.4 km-deep sediment samples, respectively. The isolates were both low G+C content, gram-positive, endospore-forming and facultative anaerobic piezophilic bacteria, closely related to Virgibacillus pantothenticus and Bacillus subtilis within the phylum Firmicutes, respectively. The optimal pressure and temperature conditions for growth were 20 MPa and 42°C for strain 19R1-5, and 10 MPa and 43°C for strain 29R7-12. Bacterial (endo)spores were observed in both the enrichment and pure cultures examined, suggesting that these piezophilic members were derived from microbial communities buried in the ~20 million-year-old coal-bearing sediments after the long-term survival as spores and that the deep biosphere may host more abundant gram-positive spore-forming bacteria and their spores than hitherto recognized.