The Phosphorus Cycle

Publisher Summary The chapter focuses on the biochemical processes by which phosphorus is incorporated into cells and those processes responsible for both phosphorus release and phosphorus sequestration in nature. Phosphorus is a vital functional and structural component of all living organisms. It occurs universally in living cells as phosphate in essential biomolecules such as nucleic acids (DNA and RNA), in energy transfer systems (NAD(P)H and ATP), and in cell membranes (phospholipids). Many of the biochemical processes are microbially mediated, and the chapter highlights the role of microbes in the phosphorus cycle. Microorganisms with active membrane-transport systems regulate the acquisition of phosphate from the environment, such as the Pts phosphate transport system of Escherichia coli. Microbial processes largely control the mobilization and immobilization of phosphorus in aquatic environments. Organic-bound phosphorus is partly assimilated and partly released as dissolved inorganic phosphorus (DIP) by the heterotrophic microbial community during organic matter mineralization. The chapter compares and contrasts phosphorus cycling in a number of representative freshwater and marine systems.