Pseudomonas enhances soil phosphorus bioavailability and maize seedling growth and affects soil microbial community

The low bioavailability of phosphorus in soil is a significant limiting factor for crop production, and inoculation with phosphate-solubilizing bacteria (PSB) has been recognized as an effective method. In this study, two strains with high phosphate-solubilizing ability, namely, Pseudomonas veronii 1416X3 and Pseudomonas sp. 1616X1, were obtained and used in pot experiments to investigate the effects of strains on phosphorus content in soil, maize plant growth, and soil microbial community. Results showed that after 4-day post-inoculation with PSB, the content of available phosphorus in the 1416X3 group (8.11 mg/L) and the 1616X1 group (6.77 mg/L) was significantly higher than that in the control group (4.97 mg/L), increasing by 1.63- and 1.36-fold, respectively. After inoculation with PSB, the microbial community of the soil rhizosphere was varied. In the 1416X3 group, shifts in the microbial community were characterized by increased relative abundances of Arthrobacter and Nocardioides, while in the 1616X1 group, the bacterial strain alters the microbial community through effective colonization and phosphate solubilization. To further elucidate the mechanisms underlying phosphorus solubilization of Pseudomonas, whole-genome sequencing of P. veronii 1416X3 and Pseudomonas sp. 1616X1 was investigated. The results revealed several genes associated with phosphate solubilization metabolism and phosphorus transport systems (pstSCAB-phoU), as well as organic acid production (gcd, pqqB-F, mqo, and ttuC). Therefore, this study establishes a basis for utilizing Pseudomonas strains as microbial phosphorus fertilizers, offering an effective and eco-friendly alternative in the pursuit of sustainable agriculture.

This study identified two Pseudomonas strains capable of efficiently activating soil phosphorus and significantly promoting maize growth. It revealed their synergistic biological mechanisms involving colonization competition, organic acid secretion, and phosphorus transport systems. The research not only provides high-quality microbial resources for developing bio-phosphate fertilizers based on indigenous functional strains but also offers a theoretical foundation and technical pathway for addressing the challenge of "high total phosphorus reserve but low available phosphorus supply" in soil, reducing the dependence on chemical phosphate fertilizers, and advancing green agricultural development.