Isolating and Characterization of Metagenomic Derived Targeted Microbial Taxa from Permafrost Soils.

            As microbes drive the biogeochemical cycles of the Earth, changes in soil microbial community composition and function due to predicted increases in global temperatures is a constantly evolving area of study. Specifically, an increasing concern has been associated with the impacts of climate change in thawing permafrost, and consequently stimulating microbial decomposition and respiration of previously sequestered carbon. Through a positive feedback loop, this can potentially further increase greenhouse gas concentrations, such as carbon dioxide and methane. These impacts are currently under investigation at a long-term experimental warming site (Carbon in Permafrost Experimental Heating Research (CiPEHR)) where a combination of metagenomic and flux-based measurements have been performed. Specifically, metagenomic binning from deep sequencing of permafrost samples has revealed the presence of large abundances of both characterized and potentially novel taxa. In this study we have isolated pure bacterial permafrost cultures on a variety of media containing varying concentrations of dilute nutrients, minimal salts and permafrost soil extracts. After incubation from 4 to 16 weeks, a subset of ~500 cultures were picked and subjected to 16S rRNA gene Sanger sequencing. This revealed a presence of multiple taxa including those matching prominent metagenomic bins including Leifsonia sp. and several unknown Acidobacteria and Actinobacteria. We also were able to culture bacteria with the highest 16S rRNA gene similarity to several previously uncultured bacteria, uncultured alpha proteobacteria, uncultured Terriglobus sp., among others. In order to characterize these potentially novel bacteria that appear to be prominent in permafrost soils, we are currently assessing their metabolic potentials through carbon use, siderophore production, nitrogen fixation and growth rate assays as well as evaluating their response to temperature variations. Overall, these bacterial isolates will improve the understanding of the microbial ecology of permafrost, the functional roles of permafrost microorganisms, and illustrates the use of metagenomic information for the isolation of novel organisms.