Phosphate-solubilizing bacteria: Recent trends and applications in agriculture

Phosphorus (P) deficiency is a major limitation of crop production. Plants take up inorganic P, which is an essential element for plant growth. Inorganic phosphorus makes up to 0.2% of plant dry weight. In the soil, the levels of inorganic P are low and present in an insoluble form. Plants can utilize phosphorus when converted to a soluble form. The beneficial soil microorganisms have mechanisms for the conversion of phosphorus. The different mechanisms by which phosphate is solubilized are acidification, chelating, and by exchange, reactions carried out by microorganisms. Bacteria, fungi, and actinomyces are the predominant microorganisms that can solubilize phosphate. Phosphate solubilization by the microflora is required to retain soil health and quality. This chapter reviews the phosphate-solubilizing efficiencies of microbial strains, their applications as bioinoculants in agricultural practices, and different strategies for application of the bacteria. Recent approaches, such as genetic engineering of phosphate-solubilizing bacteria or genetic manipulation of its genome for improved growth and solubilization, are also covered.