Thiel Vera, Hügler Michael, Ward David M, Bryant Donald A
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University ParkPA, United States.
Department Microbiology and Molecular Biology, DVGW-Technologiezentrum WasserKarlsruhe, Germany.
Front Microbiol. 2017 Jun 6;8:943. doi: 10.3389/fmicb.2017.00943. eCollection 2017.
Microbial mat communities in the effluent channels of Octopus and Mushroom Springs within the Lower Geyser Basin of Yellowstone National Park have been extensively characterized. Previous studies have focused on the chlorophototrophic organisms of the phyla and . However, the diversity and metabolic functions of the other portion of the community in the microoxic/anoxic region of the mat are poorly understood. We recently described the diverse but extremely uneven microbial assemblage in the undermat of Mushroom Spring based on 16S rRNA amplicon sequences, which was dominated by members, filamentous anoxygenic chlorophototrophs. In this study, we analyzed the orange-colored undermat portion of the community of Mushroom Spring mats in a genome-centric approach and discuss the metabolic potentials of the major members. Metagenome binning recovered partial genomes of all abundant community members, ranging in completeness from ~28 to 96%, and allowed affiliation of function with taxonomic identity even for representatives of novel and Candidate phyla. Less complete metagenomic bins correlated with high microdiversity. The undermat portion of the community was found to be a mixture of phototrophic and chemotrophic organisms, which use bicarbonate as well as organic carbon sources derived from different cell components and fermentation products. The presence of rhodopsin genes in many taxa strengthens the hypothesis that light energy is of major importance. Evidence for the usage of all four bacterial carbon fixation pathways was found in the metagenome. Nitrogen fixation appears to be limited to spp. in the upper mat layer and sp. in the undermat, and nitrate/nitrite metabolism was limited. A closed sulfur cycle is indicated by biological sulfate reduction combined with the presence of genes for sulfide oxidation mainly in phototrophs. Finally, a variety of undermat microorganisms have genes for hydrogen production and consumption, which leads to the observed diel hydrogen concentration patterns.
黄石国家公园下间歇泉盆地章鱼泉和蘑菇泉流出通道中的微生物席群落已得到广泛表征。先前的研究集中在门和门的叶绿素光养生物上。然而，对于微生物席微氧/缺氧区域中群落其他部分的多样性和代谢功能，人们了解甚少。我们最近基于16S rRNA扩增子序列描述了蘑菇泉底层多样但极其不均一的微生物群落，该群落以成员、丝状无氧叶绿素光养生物为主。在本研究中，我们以基因组为中心的方法分析了蘑菇泉微生物席群落橙色的底层部分，并讨论了主要成员的代谢潜力。宏基因组分箱获得了所有丰富群落成员的部分基因组，完整性从约28%到96%不等，甚至对于新的和候选门的代表，也能将功能与分类身份联系起来。不太完整的宏基因组箱与高微多样性相关。发现群落的底层部分是光合生物和化能生物的混合体，它们利用碳酸氢盐以及源自不同细胞成分和发酵产物的有机碳源。许多分类群中视紫红质基因的存在强化了光能至关重要这一假设。在宏基因组中发现了所有四种细菌碳固定途径使用的证据。固氮似乎仅限于上层微生物席中的属物种和底层中的属物种，硝酸盐/亚硝酸盐代谢有限。生物硫酸盐还原与主要在光合生物中存在的硫化物氧化基因相结合，表明存在一个封闭的硫循环。最后，各种底层微生物具有产氢和耗氢基因，这导致了观察到的昼夜氢浓度模式。
