Abstract:
By modulating the structure, diversity, and trophic outputs of microbial
communities, phages play crucial roles in many biomes. In oligotrophic polar deserts,
the effects of katabatic winds, constrained nutrients, and low water availability
are known to limit microbial activity. Although phages may substantially govern
trophic interactions in cold deserts, relatively little is known regarding the precise
ecological mechanisms. Here, we provide the first evidence of widespread antiphage
innate immunity in Antarctic environments using metagenomic sequence data from
hypolith communities as model systems. In particular, immunity systems such as
DISARM and BREX are shown to be dominant systems in these communities. Additionally,
we show a direct correlation between the CRISPR-Cas adaptive immunity
and the metavirome of hypolith communities, suggesting the existence of dynamic
host-phage interactions. In addition to providing the first exploration of immune systems
in cold deserts, our results suggest that phages actively challenge niche communities
in Antarctic polar deserts. We provide evidence suggesting that the regulatory
role played by phages in this system is an important determinant of bacterial
host interactions in this environment.
