Phosphorus Cycle

Microbially mediated processes in the phosphorus cycle forge a critical link between the geosphere and biosphere by assimilating phosphorus within biological molecules and contributing to chemical transformations of phosphorus in the environment. Besides acting as living reservoirs of phosphorus, microbes also contribute to the transformation of phosphorus within other nonliving reservoirs, such as rock, soils, rivers, lakes, and oceans. Microbially mediated phosphorus transformation includes processes that increase the bioavailability of phosphorus in the environment, such as weathering, solubilization, and mineralization, as well as those that decrease its bioavailability, such as assimilation and mineral formation. These large-scale environmental processes are the outcome of numerous biological pathways occurring in concert across diverse microbial communities. Genetic diversity and finely tuned regulation of gene expression allow microbes to adapt to harsh environments, and to contribute to the phosphorus cycle under numerous and diverse environmental conditions. Human alteration of the natural phosphorus cycle causes unintended consequences in microbial communities, and serious environmental, economic, esthetic, and human health problems are caused by microbial responses to the anthropogenic introduction of excess phosphorus to sensitive aquatic ecosystems.