Biogeographical patterns in soil bacterial communities across the Arctic region

The considerable microbial diversity of soils, their variety and key role in biogeochemical cycling has led to growing interest in their global distribution and the impact that environmental change might have at the regional level. In the largest study of Arctic soil bacterial communities to date, we used high-throughput sequencing to investigate the bacterial diversity from 200 widely dispersed Arctic soil samples. We identified a core microbiome, composed of 13 OTUs present at over 95% of sites, regardless of geographical location and environmental conditions. pH was identified as the key environmental driver structuring Arctic soil communities, while total organic carbon, moisture and conductivity had little effect. We were able to identify specialist, generalist and indicator taxa. Only one core biogeographical region was apparent (East Greenland, Svalbard and Iceland), although strong similarities did exist between Arctic sites separated by substantial geographical distances. We suggest that while pH might appear as the primary factor structuring soil bacterial community composition, dispersal may drive community structure in some parts of the region. Overall, Arctic soil bacterial communities, while driven by the same environmental factors as those elsewhere, were fundamentally different from those of temperate and tropical soils.