Lifting the veil on arid-to-hyperarid Antarctic soil microbiomes: a tale of two oases

Eden Zhang,Mark M Tanaka,Sin Yin Wong,Belinda C Ferrari,Aleks Terauds,Josie Van Dorst,Mark Raven,Loïc M Thibaut,Sally Crane

doi:10.1186/s40168-020-00809-w

Abstract

BackgroundResident soil microbiota play key roles in sustaining the core ecosystem processes of terrestrial Antarctica, often involving unique taxa with novel functional traits. However, the full scope of biodiversity and the niche-neutral processes underlying these communities remain unclear. In this study, we combine multivariate analyses, co-occurrence networks and fitted species abundance distributions on an extensive set of bacterial, micro-eukaryote and archaeal amplicon sequencing data to unravel soil microbiome patterns of nine sites across two east Antarctic regions, the Vestfold Hills and Windmill Islands. To our knowledge, this is the first microbial biodiversity report on the hyperarid Vestfold Hills soil environment.ResultsOur findings reveal distinct regional differences in phylogenetic composition, abundance and richness amongst microbial taxa. Actinobacteria dominated soils in both regions, yet Bacteroidetes were more abundant in the Vestfold Hills compared to the Windmill Islands, which contained a high abundance of novel phyla. However, intra-region comparisons demonstrate greater homogeneity of soil microbial communities and measured environmental parameters between sites at the Vestfold Hills. Community richness is largely driven by a variable suite of parameters but robust associations between co-existing members highlight potential interactions and sharing of niche space by diverse taxa from all three microbial domains of life examined. Overall, non-neutral processes appear to structure the polar soil microbiomes studied here, with niche partitioning being particularly strong for bacterial communities at the Windmill Islands. Eukaryotic and archaeal communities reveal weaker niche-driven signatures accompanied by multimodality, suggesting the emergence of neutrality.ConclusionWe provide new information on assemblage patterns, environmental drivers and non-random occurrences for Antarctic soil microbiomes, particularly the Vestfold Hills, where basic diversity, ecology and life history strategies of resident microbiota are largely unknown. Greater understanding of these basic ecological concepts is a pivotal step towards effective conservation management.

Highlights

Resident soil microbiota play key roles in sustaining the core ecosystem processes of terrestrial Antarctica, often involving unique taxa with novel functional traits
Amplicon sequencing yield and coverage We recovered a total of 60,495,244 high-quality bacterial 16S rRNA gene sequences, which clustered into 36,251 operational taxonomic units (OTUs) at 97% identity cutoff
Our micro-eukaryotic and archaeal runs yielded a total of 1,299,519 18S rRNA and 13,373,072 16S rRNA gene sequences after read-quality filtering, which respectively clustered at 97% into 1511 and 589 OTUs (Table S1)

Summary

Introduction

Resident soil microbiota play key roles in sustaining the core ecosystem processes of terrestrial Antarctica, often involving unique taxa with novel functional traits. We combine multivariate analyses, co-occurrence networks and fitted species abundance distributions on an extensive set of bacterial, microeukaryote and archaeal amplicon sequencing data to unravel soil microbiome patterns of nine sites across two east Antarctic regions, the Vestfold Hills and Windmill Islands. To our knowledge, this is the first microbial biodiversity report on the hyperarid Vestfold Hills soil environment. 100 km to the north lie the Vestfold Hills, a large expanse of low-lying hilly country deeply indented by sea-inlets and lakes [3, 4] These diverse edaphic habitats are a legacy of age-involving varied geological and glaciological processes [5]. In our understanding of soil microbiota across the different bioregions of terrestrial Antarctica, addressing these deficiencies will improve our understanding of Antarctic microbial biogeography and guide future conservation planning strategies [10]

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