[FeFe]-hydrogenase in Yellowstone National Park: evidence for dispersal limitation and phylogenetic niche conservatism

Abstract

Hydrogen (H 2 ) 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 H 2 in microbial communities. In this study, we examined the [FeFe]-hydrogenase gene (hydA) as a proxy for fermentative bacterial H 2 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 H 2 . 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.

Patterns of [FeFe] Hydrogenase Diversity in the Gut Microbial Communities of Lignocellulose-Feeding Higher Termites

“…Hydrogenase sequences taken from T. primitia ZAS-2 and T. primitia ZAS-9 are labeled as ZAS-2 (HndA1) and ZAS-9 (HndA), respectively. drogenase sequences from unique ecosystems, as evidenced by sequence similarity and uniqueness, have been reported by Ballor and Leadbetter and by Boyd et al (2,5,6).…”

“…Functional variation is known to be linked to increased ecosystem function (45). In their study of hydrogenase sequence diversity and phylogeny, Boyd et al propose that an increase in phylogenetic diversity that they observed in slightly acidic geothermal springs may result in a more resilient community able to "better respond to change in both physical and chemical conditions in these environments due to seasonal hydrological and chemical changes" (5).…”

Carbon Source Preference in Chemosynthetic Hot Spring Communities

“…Microcosm assays were conducted to determine the affinity constant (K m ; the concentration at which the formate conversion velocity reaches one-half of its maximum rate) for chemosynthetic microbial communities in the same 5 10.0 M. Microcosms were prepared, incubated, and analyzed for formate conversion activity as described below. To determine formate conversion rates, the rate at which CO 2 was produced from formate oxidation (the methods are described below) was combined with the rate of C assimilation from formate.…”

“…ife in environments with temperatures that exceed the upper limit of photosynthesis (ϳ73°C) is supported by chemical energy (1)(2)(3)(4)(5). In the case of high-temperature (Ͼ73°C) terrestrial hot spring environments, the prevalence of members of the bacterial phylum Aquificales has been interpreted to reflect the importance of lithoautotrophic metabolism in supporting communities inhabiting these systems (6)(7)(8)(9)(10)(11).…”

Expression of different types of [FeFe]-hydrogenase genes in bacteria isolated from a population of a bio-hydrogen pilot-scale plant

“…So far, the high diversity of [FeFe]-hydrogenases has been studied both in natural environments [25][26][27] and several pilot scale plants for H2 production [28][29][30].…”