Microbial phosphorus cycling in terrestrial ecosystems.

Phosphorus is an essential yet often limiting macronutrient that shapes primary productivity and microbial activity in terrestrial ecosystems. Unlike carbon and nitrogen cycles, which have gaseous phases, the terrestrial phosphorus cycle is primarily governed by soil biogeochemistry, wherein microorganisms orchestrate key transformations. This Review synthesizes current knowledge of the microbial phosphorus cycle, emphasizing the diverse mechanisms used by bacteria, fungi and archaea to mobilize phosphorus (for example, via phosphatases such as PhoA and PhoD and organic acids such as citrate) and to directly enhance plant phosphorus uptake. We explore the ecological significance of these processes in maintaining soil health, supporting ecosystem productivity and influencing carbon sequestration. We propose the Microbial Phosphorus Adaptive Evolution Theory (MPAET): chronic phosphorus scarcity drives evolutionary and ecological shifts in microbial communities towards higher scavenging investment, polyphosphate handling and lipid remodelling. Furthermore, we examine how environmental factors, land use and climate modulate these shifts (for example, phoD expression increases under phosphorus stress), with cascading effects on ecosystem function and global phosphorus availability. New technologies such as metagenomics,