Biomics

We report the isolation and characterization of Rhodopseudomonas sp. strain RCAM05734 from the upper horizon of Holocene permafrost on the southern shore of Isfjorden, Svalbard. The strain was recovered on R2A at 5°C and sequenced using Oxford Nanopore long reads; assembly produced a single circular chromosome of 6.65 Mb (GC 63.9%) encoding 6,183 predicted proteins and 65 RNA genes (GenBank CP199742; SRA SRS26238712). Although the 16S rRNA gene shows high similarity (98%) to several Rhodopseudomonas type strains, average nucleotide identity values (78–80%) indicate that RCAM05734 is genomically distinct and may represent a novel species. The genome contains three fix loci and an almost complete nif gene complement, consistent with potential for nitrogen fixation under microaerobic conditions. Genes implicated in plant‑associated functions (acdS/acdR, iaaM/iaaH), multiple cold‑shock proteins, and accessory nod regulatory loci were also identified. RCAM05734 encodes extensive aromatic‑compound catabolic pathways, including both catechol and protocatechuate branches of the β‑ketoadipate pathway and meta‑cleavage enzymes. Phenotypic profiling (Biolog GEN III) revealed utilization of diverse mono‑ and disaccharides and selected carboxylic acids, limited halotolerance (growth at 1% NaCl) and activity at mildly acidic pH. Collectively, genomic and physiological data suggest that RCAM05734 harbors metabolic versatility relevant to carbon and nitrogen turnover, stress tolerance, and potential plant‑growth promotion in cold Arctic conditions.

Rhodopseudomonas sp., permafrost, phenotypic profiling, Oxford Nanopore long-read sequencing

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