Biotechnological Applications of Phosphate Solubilizing Microorganisms: Biological Alternative to Improve Phosphorus Availability

Phosphorus (P) is abundant in nature and, along with nitrogen and potassium, is regarded as a crucial component of plants. Plants acquire P in the form of monovalent (H2PO4) and divalent (HPO4) orthophosphate anions from the soil solution. Although the amount of P in the soil is generally important, the forms available to plants are minimal. The inorganic P and organic P are the forms that are unavailable to plants; the inorganic forms are associated with calcium in alkaline soils and aluminum and iron compounds in acidic soils, whereas organic P forms are associated with organic matter. Furthermore, P is quickly immobilized and blocked in the soil; therefore, a large amount of the phosphate input during chemical fertilization is immobilized. P-solubilizing microorganisms, through rhizospheric and symbiotic relationships, considerably modify the quantity of P that the plant needs to acquire for its growth. The number of species identified as P solubilizers has increased recently as a result of numerous studies on phosphate solubilization by microorganisms; a variety of these microorganisms, including bacteria, fungi, and actinomycetes, are capable of P solubilization. Moreover, several studies have investigated the P-solubilizing microorganisms’ performance as biofertilizers with the goal of enhancing crop productivity while preserving soil health. Moreover, the biotechnological applications of these microorganisms as a biological alternative to chemicals have now become a focus of attention for several researchers and agricultural decision-makers. This chapter focuses on the variety of microorganisms that can solubilize phosphate, and how they can be used in agriculture as eco-friendly approaches to enhance the availability of phosphorus in soil.