Chapter 11 - Phosphate solubilization by microorganisms: Overview, mechanisms, applications and advances

Abstract

Phosphorus is known as the master key element among all the elements required for plant growth. The diverse soil phosphorus forms can be categorized as soluble orthophosphates, insoluble inorganic and insoluble organic phosphates. Large reactivity of orthophosphate ions with numerous soil constituents convert it into insoluble inorganic and insoluble organic forms. Therefore, it is the least mobile element in most soil and is unavailable for plant uptake. However, numerous microorganisms can enhance plant phosphorus nutrition by solubilizing insoluble phosphates. Phosphate solubilizing microorganisms have diverse mechanisms that aid in the solubilization of fixed or unavailable phosphorus. Different mechanisms of inorganic phosphate solubilization are acidification due to the production of organic acids, inorganic acids, and H+ excretion, exopolysaccharide production, and siderophore production. Phosphatase, phytase, and C–P lyase enzymes aid in the solubilization of organic phosphate. Potential phosphate solubilizing microorganisms have been formulated as biofertilizer and extensively applied in fields for the promotion of plant growth. Interestingly, the property of phosphate solubilization has also found tremendous application in the field of phytoremediation. This chapter presents an overview of phosphate solubilizing microorganisms, different mechanisms used by microorganisms to solubilize insoluble phosphate, and finally applications of phosphate solubilizing microorganisms.