Department of Chemistry and Biochemistry, Astrobiology Biogeocatalysis Research Center, Montana State University, Bozeman, 59717, USA.
ISME J. 2010 Dec;4(12):1485-95. doi: 10.1038/ismej.2010.76. Epub 2010 Jun 10.
Hydrogen (H₂) has an important role in the anaerobic degradation of organic carbon and is the basis for many syntrophic interactions that commonly occur in microbial communities. Little is known, however, with regard to the biotic and/or abiotic factors that control the distribution and phylogenetic diversity of organisms which produce H₂ in microbial communities. In this study, we examined the [FeFe]-hydrogenase gene (hydA) as a proxy for fermentative bacterial H₂ production along physical and chemical gradients in various geothermal springs in Yellowstone National Park (YNP), WY, USA. The distribution of hydA in YNP geothermal springs was constrained by pH to environments co-inhabited by oxygenic phototrophs and to environments predicted to have low inputs of abiotic H₂. The individual HydA asssemblages from YNP springs were more closely related when compared with randomly assembled communities, which suggests ecological filtering. Model selection approaches revealed that geographic distance was the best explanatory variable to predict the phylogenetic relatedness of HydA communities. This evinces the dispersal limitation imposed by the geothermal spring environment on HydA phylogenetic diversity even at small spatial scales. pH differences between sites is the second highest ranked explanatory variable of HydA phylogenetic relatedness, which suggests that the ecology related to pH imposes strong phylogenetic niche conservatism. Collectively, these results indicate that pH has imposed strong niche conservatism on fermentative bacteria and that, within a narrow pH realm, YNP springs are dispersal limited with respect to fermentative bacterial communities.
氢气（H₂）在有机碳的厌氧降解中起着重要作用，是许多微生物群落中经常发生的共生相互作用的基础。然而，对于控制产生 H₂的微生物群落中生物和/或非生物因素的了解甚少。在这项研究中，我们研究了 [FeFe]-氢化酶基因（hydA）作为发酵细菌 H₂产生的替代物，以研究美国怀俄明州黄石国家公园（YNP）不同温泉中的物理和化学梯度。YNP 温泉中 hydA 的分布受到 pH 的限制，与含氧光合生物共栖的环境以及预计缺乏非生物 H₂输入的环境有关。与随机组装的群落相比，YNP 温泉中单个 HydA 组合更为相关，这表明存在生态过滤。模型选择方法表明，地理距离是预测 HydA 群落系统发育相关性的最佳解释变量。这表明，即使在小的空间尺度上，温泉环境对 HydA 系统发育多样性的扩散限制。站点之间的 pH 差异是 HydA 系统发育相关性的第二个最高解释变量，这表明与 pH 相关的生态学对 pH 施加了强烈的系统发育生态位保守性。总的来说，这些结果表明，pH 对发酵细菌施加了强烈的生态位保守性，并且在狭窄的 pH 范围内，YNP 温泉在发酵细菌群落方面受到扩散限制。
