Molecular Characterization of Phosphate Solubilizing Bacteria from Cereal Crop Rhizospheres: A Review

Phosphorus (P) is an essential macronutrient for plant growth, yet a large fraction of soil phosphorus remains unavailable due to its fixation in insoluble forms. Excessive reliance on chemical fertilizers to overcome this deficiency has raised serious economic and environmental concerns. Phosphate solubilizing bacteria (PSB) represent an eco-friendly and sustainable alternative, as they mobilize insoluble phosphates through mechanisms such as organic acid secretion, phosphatase activity, and siderophore production. Cereal crops, including rice, wheat, and maize, are particularly dependent on phosphorus for optimum productivity, making the rhizosphere of these crops an important niche for PSB research. Recent advances in molecular techniques such as 16S rRNA gene sequencing, functional gene analysis, metagenomics, and phylogenetic studies have enabled precise characterization of novel PSB strains and their functional attributes. This review highlights the diversity and mechanisms of PSB in cereal rhizospheres, with emphasis on molecular characterization under field conditions. Furthermore, it discusses their role in sustainable crop production, current challenges in large-scale application, and future prospects for integrating molecularly characterized PSB strains into biofertilizer technology. Overall, PSB hold significant promise for reducing chemical fertilizer dependency and improving global food security.