Genomic and phenotypic characterization of phosphate-solubilizing strain YNK-FB0058, which potentially represents a novel species within the genus Phyllobacterium

Abstract Background Phosphate-solubilizing bacteria are soil-dwelling probiotics that promote plant growth and convert unavailable phosphorus into absorbable forms for plants. A potentially novel Phyllobacterium strain YNK-FB0058 isolated from the rhizosphere of safflower in tobacco-safflower rotation fields was used as the research material in this study. Whole-genome sequencing and in vitro verification tests were conducted to explore its genetic basis and functional traits. Results Phylogenetic analysis based on 16S rRNA and 31 housekeeping genes, combined with genomic comparisons of ANI and dDDH, confirmed that strain YNK-FB0058 represents a potential novel species of the Phyllobacterium . Its complete genome size is 4,694,147 bp with a GC content of 61.14%, and a total of 4,459 CDSs were annotated. The genome harbors gene clusters involved in inorganic phosphorus solubilization, organic phosphorus mineralization, phosphorus transport and regulation. It also carries growth-promoting genes related to IAA synthesis, nitrogen fixation, siderophore production and zinc solubilization. The strain exhibited high efficiency in solubilizing organic and inorganic phosphorus, with solubilization capacities of 566.3 mg/L and 474.46 mg/L respectively, and secreted IAA at 19.319 µg/mL. It also showed activities of nitrogen fixation, zinc solubilization and siderophore synthesis. Inoculation with this strain significantly increased plant height, stem diameter, leaf area and biomass of flue-cured tobacco, elevated nitrogen and phosphorus contents and enzyme activities in rhizosphere soil, and promoted phosphorus accumulation in tobacco plants. Conclusions YNK-FB0058 is a potentially novel species of the genus Phyllobacterium , with highly efficient phosphate-solubilizing capability and multiple plant growth-promoting traits. This strain provides a high-quality microbial resource and theoretical basis for reducing chemical phosphorus fertilizer application and developing high-efficiency microbial inoculants in green agriculture.