Role of Phosphatase Enzymes in Soil

Phosphatases have been extensively studied in soil, as shown by some reviews because they catalyse the hydrolysis of ester–phosphate bonds, leading to the release of phosphate (P), which can be taken up by plants or microorganisms. It has been shown that the activities of phosphatases (like those of many hydrolases) depend on several factors such as soil properties, soil organism interactions, plant cover, leachate inputs and the presence of inhibitors and activators. Phosphatases are enzymes catalysing the hydrolysis of both esters and anhydrides of phosphoric acid and, according to the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology, they can be classified as phosphoric monoester hydrolases or phosphomonoesterases (EC 3.1.3), phosphoric diester hydrolases or phosphodiesterases(EC 3.1.4), triphosphoric monoester hydrolases (EC 3.1.5) and enzymes acting on phosphoryl-containing anhydrides (EC 3.6.1) and on P–N bonds (EC 3.9). Phosphatases can also be subdivided according to their regulation (e.g. calmodulin), the requirements of metal cations for their activity (e.g. Mg2þ and Ca2þ) and their sensitivity to various phosphatase inhibitors. Phosphomonoesterases include acid and alkaline phosphomonoesterase (which hydrolyse monoester bonds including mononucleotides and sugar phosphates), phosphoprotein phosphatases (which hydrolyse phosphoester bonds of phosphoserines, phosphothreonines or phosphotyrosines), phytases (EC 3.1.3.26 for 4-phytase and EC 3.1.3.8 for 3-phytase, which hydrolyse all six phosphate groups from inositol hexaphosphate) and nucleotidases.