Viruses keep Arctic microbial adaptation from its breaking point

Abstract

International audienceMicrobial adaptation to changes in the environment is the first step to evolution. The acquisition of genes and development of novel enzymes in response to environmental perturbations are critical to successful adaptation. But can microorganisms in extreme environments, such as the Arctic, adapt fast enough to respond to rapid anthropogenic changes? Pollutants are tilting biogeochemical cycles and climate change is causing glacial retreat and possibly introducing a flow of microorganism into new niches. Rapid adaptation to environmental perturbations could be attained through transduction, virus mediated transfer of genetic material between bacteria. Viruses have been suggested to play a key role in polar environments, and the relatively high virus to bacteria ratio might provide the answer to how cold adapted communities are dealing with these changes. Moreover, the potential broad host ranges would make them effective vectors. As an example a strong signature of phages for Ralstonia, a known carrier of mercury resistance genes, was seen in the virome of an Arctic glacier relative to other environmental viromes. Data on environmental viruses is scarce and tracking their interactions with bacteria has only been addressed through single strain based experiments. Nevertheless, CRISPRs (Clustered Interspaced Short Palindromic Repeats) provide a history of viral-­‐host interactions and might document this crucial viral influence on Arctic microbial community adaptation. Thus comparative CRISPR metagenomics will be used to describe the possible interaction between viruses and microorganisms in different ecosystems