Plant growth promoting traits of selected psychrotolerant bacteria: a genomic basis of biocontrol, nutrient acquisition and stress tolerance

Psychrotolerant, plant growth promoting microorganisms represent valuable allies for sustainable agriculture in cold-stressed environments. This study employed whole-genome sequencing and comparative genomics to characterize three such psychrotolerant bacterial isolates possessing plant growth promoting traits. Average Nucleotide Identity (ANI), Type (Strain) Genome Server and phylogenomic reconstruction identified the isolates as Comamonas jiangduensis, Pseudomonas rhodesiae, and a putative novel Acinetobacter species. Functional profiling using PGPg_Finder revealed that all isolates possessed genes associated with plant growth promotion and abiotic stress tolerance, with P. rhodesiae boasting the most extensive repertoire of plant-beneficial genes. Pangenome analysis highlighted both shared and isolate-specific genetic features, providing insight into the functional differentiation among taxa. Moreover, the diverse biosynthetic gene clusters (BGCs) support the potential of these isolates in biocontrol, nutrient acquisition, and stress mitigation. RhizoSMASH analysis further indicated the genetic capacity for utilization of root exudates, suggesting rhizosphere compatibility despite the digestate origin of the isolates. Whilst predicted virulence determinants were detected in P. rhodesiae, it is postulated that these genes are related to ecological fitness and isolate resilience, rather than its pathogenicity; nevertheless, comprehensive biosafety assessment is required prior to application. Overall, the findings underscore the potential of all isolates for the enhancement of crop performance and highlight psychrophilic anaerobic digestate as an underexplored microbial reservoir. Notably, this study uniquely reports the first genome-enabled characterization of a putative novel cold-tolerant Acinetobacter species.