摘要
【背景】非致病性Epsilonproteobacteria广泛存在于全球各种不同的自然环境中,特别是一些极端生境如深海热液喷口,并且经常在微生物群落中作为优势物种被发现。然而,由于现阶段培养技术的限制,仅有为数不多的深海热液Epsilonproteobacteria被分离培养,极大限制了对其生理特征、代谢方式以及生态功能的深入认识。【目的】研究深海热液未培养Epsilonproteobacteria的进化地位、代谢潜能及其在原位生态系统中可能发挥的作用。【方法】基于宏基因组学Binning的方法,从采集自东太平洋海隆深海热液烟囱体样本中构建4个高质量的Epsilonproteobacteria基因组Bin225、Bin51、Bin54和Bin189,并进行了系统发育和代谢途径的分析。【结果】Bin189在系统发育树上相对独立于其他所有已知的Epsilonproteobacteria类群,而其余3个重构基因组都与Nitratiruptor sp. SB155-2具有较近的亲缘关系。在代谢潜能方面,所有的基因组除了都含有sqr硫氧化和rTCA碳固定途径的基因以外,也同时具有脂多糖输出转运子和多种分泌系统。Bin189显示出与其它基因组显著不同的代谢特征,其中还检测到与有机物和氨基酸转运相关的功能基因。而其他的3个基因组均具有完整的反硝化途径的功能基因,其中2个还具有Sox系统、氢化酶和鞭毛移动系统。【结论】Bin189可能是一种新发现的深海热液兼性化能营养型Epsilonproteobacteria,推测其余的3个类群能够利用硫化物和氢气作为能源进行化能自养生长。考虑到它们多样的代谢潜能,这些Epsilonproteobacteria类群很可能在深海热液微生物群落的形成发展和地球化学元素循环中发挥重要作用。
[Background] Nonpathogenic Epsilonproteobacteria globally distributes in diverse natural environments, especially extreme environments like deep sea hydrothermal vents, are usually detected in microbial communities as a dominant microbial group. Only few hydrothermal Epsilonproteobacteria species have been isolated due to the limitation of current culture technology, which significantly influences our further understanding about their physiological features, metabolic pathways and ecological roles. [Objective] Gaining insight into the phylogenetic position, metabolic potentials and putative roles of uncultured Epsilonproteobacteria in the deep sea hydrothermal communities and vent ecosystems. [Methods] We analyzed the phylogeny and metabolic pathway of four Epsilonproteobacteria reconstructed from the East Pacific Rise deep sea hydrothermal chimney sample based on metagenomic Binning technology. [Results] Bin189 is phylogenetically independent from all other known Epsilonproteobacteria, whereas the other three reconstructed genomes have closed relationship with Nitratiruptor sp. SB155-2. In metabolic potentials, all of reconstructed genomes have the sqr and rTCA carbon fixation pathway related genes, besides they all have the lipopolysaccharide exporter system and multiple secretion system. However, Bin189 has the extra organic matter and amino acid transporters, all of the other three genomes have the complete denitrification pathway and two of them also have the Sox system, hydrogenase as well as the flagella system. [Conclusion] Bin189 very likely is a kind of novel heterotrophic Epsilonproteobacteria detected in the deep sea hydrothermal environments, whereas the other three chemoautotrophic taxa are capable of oxidizing diverse reduced sulfur compounds and hydrogen as energy source. Consequently, these Epsilonproteobacteria are supposed to play crucial roles in the colonization and development of the hydrothermal microbial communities as well as the deep sea geochemical element cycling.
引文
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