Acid phosphatases in the context of the global phosphorus cycle

Abstract Phosphorus is an essential yet limited element that regulates biological productivity and ecological balance within the Earth’s interconnected biogeochemical systems. Its transformations link the lithosphere, hydrosphere, and biosphere; however, the absence of a gaseous phase makes phosphorus one of the least mobile nutrients. Microorganisms play a pivotal role in maintaining its bioavailability through mineralization, solubilization, and redox reactions. Geological and biological evidence demonstrates that fluctuations in phosphorus availability have profoundly influenced ocean oxygenation, biological diversification, and ecosystem evolution. Human activities such as mining, deforestation, and fertilizer overuse have intensified phosphorus fluxes, leading to eutrophication, soil depletion, and disruption of natural nutrient cycles. Understanding phosphorus mobilization, storage, and microbial mediation is essential for advancing sustainable nutrient management. In soils and aquatic environments, phosphorus mobility is governed by the interplay between immobilization and microbial mobilization. Immobilization occurs via biological uptake, storage in organic forms, and mineral precipitation as apatite. Mobilization is driven by phosphate-solubilizing microorganisms in the rhizosphere. These microorganisms secrete organic acids, metallophores, and phosphatases that convert insoluble compounds into available orthophosphate. Root exudates and regulatory systems such as the Pho regulon coordinate microbial and plant phosphorus acquisition thus, sustaining soil fertility and productivity. Alkaline and acid phosphatases are enzymes that hydrolyze organophosphorus compounds, releasing orthophosphate. Their structural and mechanistic diversity underpins their ecological versatility. Detailed bioinformatic analysis have identified three classes of bacterial acid phosphatases and at least eight major clades of fungal phosphatases. Beyond their environmental role, these enzymes offer promising applications in biotechnology.