Polyphasic taxonomy and genome mining of Desertivibrio insolitus gen. nov., sp. nov., a novel psychrotolerant pectin-degrading actinobacterium isolated from desert soil

Abstract

Extreme arid environments harbor diverse yet underexplored microorganisms with unique ecological adaptations and significant biotechnological potential. Here, we characterized a novel actinobacterium, strain SYSU D00978^T, isolated from desert soil in the Gurbantunggut Desert, Xinjiang, China. The strain was Gram-stain-positive, aerobic, curved-rod-shaped, non-motile, catalase-positive, and oxidase-negative. Phylogenetic analysis based on the 16S rRNA gene placed it within the family Microbacteriaceae, showing highest similarity to Schumannella soli 10F1D-1^T (97.3 % sequence identity) and Schumannella luteola KHIA^T (97.2 %), while phylogenomic analyses consistently supported its distinction from known genera. The genome of SYSU D00978^T was 2.98 Mb with a G + C content of 70.8 %. Comparative genomic analysis showed that its average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values against the closest related taxa were below the species delineation thresholds (ANI: 95–96 %; dDDH: 70 %). The strain exhibited psychrotolerance and pectin-degrading activity, indicating ecological adaptation to cold periods and involvement in organic matter turnover in desert soils. Functional annotation identified genes linked to oxidative and osmotic stress responses, carbon starvation, cold and heat shock, DNA repair, and ribosome hibernation, reflecting resilience to extreme conditions. Additionally, biosynthetic gene clusters for terpene, type III polyketide synthase, and beta-lactone suggested potential for novel bioactive compounds. Phenotypic and chemotaxonomic traits further supported its taxonomic novelty. Based on polyphasic evidence, strain SYSU D00978^T (= CGMCC 1.18633^T = MCCC 1K04997^T = KCTC 49492^T) represents a novel species of a new genus within the family Microbacteriaceae, for which the name Desertivibrio insolitus gen. nov., sp. nov. is proposed. This study expands our understanding of microbial diversity and ecological adaptations in extreme desert environments and provides a valuable resource for future biotechnological exploration.