Genome sequencing and assembly of two candidate species within the proposed genus Gelidimonas

This project involves the genomic and taxonomic characterization of two psychrophilic bacterial strains (D2 and D11) isolated from ornithogenic soils of South Spitsbergen (Svalbard, High Arctic). Genome-based phylogenomic analyses place both strains within the family Oxalobacteraceae (class Betaproteobacteria, phylum Pseudomonadota) and support their classification as two distinct species forming a newly proposed genus, Gelidimonas gen. nov.Gelidimonas denitrificans sp. nov. (type strain D11) is a Gram-negative, motile, facultatively anaerobic heterotroph capable of nitrate reduction and complete denitrification. Its genome comprises a 3.67 Mb circular chromosome and two plasmids (26.3 kb and 16.3 kb).Gelidimonas diazotrophica sp. nov. (type strain D2) is a facultative chemolithoautotroph that fixes nitrogen and assimilates CO2 using molecular hydrogen as an energy source. Its genome consists of a 3.85 Mb circular chromosome and one plasmid (26.3 kb).Comparative genomic analyses (ANI, dDDH, AAI, and core-proteome phylogeny) confirm that D2 and D11 represent two separate species within a novel genus, clearly differentiated from all currently described Oxalobacteraceae lineages. Both species are psychrophilic, with growth between 5 and 15/20 deg C and an optimum at 10 deg C, and are involved in nitrogen cycling processes in Arctic ornithogenic soils.Together, these genomes expand current knowledge of microbial diversity in polar ecosystems and highlight the ecological significance of psychrophilic denitrifiers and diazotrophs under cold-climate conditions.