Core-Periphery Microbiota Organization Is Associated with Functional Resilience in High Arctic Svalbard Soils

Experimental Objective: Arctic soils harbor diverse bacterial communities that regulate carbon and nutrient cycling under persistent coldness, low-nutrient availability, and episodic freeze-thaw. However, the extent to which bacterial community stability versus spatial specialization structures these communities remains unresolved. Methods: This study characterized bacterial assemblages (microbiota) across 6 geographically distinct Svalbard soil sites using 16S ribosomal RNA gene sequencing, integrated with alpha- and beta-diversity comparisons, taxonomic profiling, linear discriminant analysis effect size (LEfSe) candidate biomarkers, core microbiota analysis, co-occurrence network, and predictive functional inference. Results: Proteobacteria dominated across Svalbard soil sites, accompanied by Actinobacteria, Acidobacteria, and Bacteroidetes. Taxa compositions and beta-diversity revealed spatial structuring, with Wahlbergøya and Northernmost Island relatively more unique community configurations. Consistently, LEfSe identified candidate site-specific taxa, i.e., sulfur-oxidizing bacteria and Acidobacteria, suggesting local environmental selection. The conserved core phylotype analysis indicated microbiota patterns associated with localized geographics and unraveled 48-phylotype core microbiota spanning 5 phyla. Functional predictions demonstrated dual-functional structures: (a) conserved functions in genome maintenance, membrane transport, and central carbon and amino acid metabolisms and (b) site-specific functional enrichments linked to stress responses, redox balance, xenobiotic degradation, and utilization of recalcitrant substrates. Integration of core microbiota taxonomic, network, and functional analyses further revealed 4 mechanistic resilience strategies: genome integrity maintenance, membrane adaptation, oxidative stress alleviation, and flexible resource (i.e., recalcitrant substrates) utilization. These strategies highlighted how shared core taxa collectively translated into microbial adaptive process and persistence, across sites. Conclusions: These findings underpinned that High Arctic soil microbiota were structured consistently with functional plasticity that supported Arctic ecosystem processes.