The rhizosphere soil of invasive plants may harbor abundant phosphate-solubilizing microbial resources. This study aims to isolate and screen highly efficient phosphate-solubilizing strains from their rhizosphere soil, thereby identifying functional strains with application potential for soil improvement and sustainable agricultural development.

Using rhizosphere soil samples collected from 10 invasive plants across different habitats, efficient phosphate-solubilizing strains were isolated via screening on solid medium and quantified by the molybdenum-antimony colorimetric method. Molecular identification was performed, and two novel strains were selected for further analysis of their phosphate-solubilizing capacity and whole-genome sequencing. Genome assembly, functional annotation, and mining of potential phosphorus-cycling gene clusters and mechanisms were conducted to evaluate their phosphorus utilization potential.

Sixteen efficient phosphate-solubilizing strains were isolated from the rhizosphere soils of different invasive plants. Two novel strains, designated IPSM-1 and IPSM-2, were identified based on 16S rDNA sequencing. The phosphate-solubilizing capacity assay showed a significant difference between the two strains: IPSM-2 released up to 448.82 mg·L^-1 of soluble phosphate, significantly higher than the 243.00 mg·L^-1 released by IPSM-1. Phylogenetic analysis using the neighbor-joining method in MEGA software confirmed that IPSM-1 and IPSM-2 belong to the genus Priestia and Pseudomonas, respectively. After 10 d of culture, the ratio of phosphate-solubilizing zone diameter to colony diameter (D/d) was 2.07 for IPSM-1 and 2.41 for IPSM-2, indicating stronger solubilization potential by IPSM-2. Growth curve analysis revealed that IPSM-1 exhibited better growth characteristics, whereas IPSM-2 demonstrated higher phosphate-solubilizing potential. Scanning electron microscopy further revealed clear differences in colony morphology, cell structure, and growth features between the two strains. Genomic analysis showed that IPSM-1 has a genome size of 5961332 bp with a GC content of 37.48%. Its functional genes were notably enriched in pathways related to carbohydrate metabolism, amino acid transport, and signal transduction, along with a high number of phosphorylation-related genes. In contrast, IPSM-2 possesses a larger genome of 8746878 bp with a GC content of 67.15%. Besides stronger enrichment in the aforementioned metabolic and signaling pathways, it also contains significantly more genes involved in transmembrane transport and metal ion binding, as well as relatively complete gene clusters for organic acid synthesis and secretion.

The two novel phosphate-solubilizing strains obtained in this study exhibit high phosphate-solubilizing efficiency. Among them, IPSM-1 may primarily achieve phosphorus dissolution through intracellular phosphorus metabolism pathways, making it more suitable for long-term low-phosphorus stress environments. IPSM-2 exhibits enhanced phosphorus dissolution capacity through multiple mechanisms such as secretion of organic acids and chelation of metal ions. Both strains provide excellent microbial resources for developing efficient microbial fertilizers.