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.IMPORTANCE In Antarctic environments, the combination of both abiotic and biotic stressors results in simple trophic levels dominated by microbiomes. Although the past two decades have revealed substantial insights regarding the diversity and structure of microbiomes, we lack mechanistic insights regarding community interactions and how phages may affect these. By providing the first evidence of widespread antiphage innate immunity, we shed light on phage-host dynamics in Antarctic niche communities. Our analyses reveal several antiphage defense systems, including DISARM and BREX, which appear to dominate in cold desert niche communities. In contrast, our analyses revealed that genes which encode antiphage adaptive immunity were underrepresented in these communities, suggesting lower infection frequencies in cold edaphic environments. We propose that by actively challenging niche communities, phages play crucial roles in the diversification of Antarctic communities.
Highlights
IntroductionDiversity, and trophic outputs of microbial communities, phages play crucial roles in many biomes
By modulating the structure, diversity, and trophic outputs of microbial communities, phages play crucial roles in many biomes
The distribution of antiphage defense mechanisms shows a diversity of innate immunity genes
Summary
Diversity, and trophic outputs of microbial communities, phages play crucial roles in many biomes. 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. Photosynthetic assemblages found below translucent rocks, are widely distributed across hot and cold deserts [13,14,15] In these arid environments, the absence of plants and larger organisms makes these niche communities, with relatively simple trophic structures, ideal systems for understanding microbial community dynamics [16]. Microarray analysis of lithic niches identified an even greater phage diversity, including signatures of RNA bacteriophages of the family Leviviridae, ssDNA phage of the family Microviridae, and nontailed dsDNA tectiviruses [32] Together, these observations suggest that phages may play an important role in microbial community structures and functions
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