Plants impact structure and function of bacterial communities in Arctic soils

Abstract

Microorganisms are prime drivers of ecosystem functions in the Arctic, and they are essential for vegetation succession. However, very little is known about the phylogenetic and functional diversities of the bacterial communities associated with Arctic plants, especially in low organic matter soils. Here, we studied the diversity and community structure of the total and diazotrophic bacterial communities in the rhizospheres of two Arctic pioneer plant species, Oxyria digyna and Saxifraga oppositifolia, as well as the phenotypic profiles of these communities. Plant and soil samples were harvested from four sampling sites located in the low (Finnish) and high (Norwegian) Arctic. Bacterial diversities and community structures were determined with 16S rRNA and nifH gene-targeted PCR and T-RFLP profiling. The phenotypic (functional and antibiotic resistance) profiles of the soil bacterial communities were determined with BIOLOG Gen III plates. Location and soil type, as well as plant species were shown to significantly influence the bacterial community structures. This was evident from the clustering of the communities per sampling location and per plant species in ordination plots. Geographical location as well as, plants also influenced the functional profiles of the soil bacterial communities. The antibiotic resistance profiles were associated with the location the communities were derived from, whereas the abilities to tolerate oxidative stress and specific antibiotics were associated with the rhizosphere communities