SOME ASPECTS OF ENVIRONMENTAL REGULATION OF MICROBIAL PHOSPHORUS METABOLISM

Abstract

This chapter discusses some aspects of environmental regulation of microbial phosphorus metabolism. Polyphosphates are primarily a full-fledged reserve of activated phosphate, which makes microbial metabolism more independent of environmental conditions and, in particular, allows the regulation of ATP and other nucleotide levels in the cell. The direction of biochemical processes in microbial cells strongly depends on phosphate concentration in the growth medium. High-molecular weight polyphosphates can play an important role in microbial activity, switching over their primary metabolism to synthesis of antibiotics and, probably, other secondary metabolites. Many environmental factors such as concentrations of various metal ions, amino acids and phosphate in the medium, and dehydration, greatly influence polyphosphate metabolism and its pathways. In autotrophic organisms, relatively low-molecular polyphosphates are primarily synthesized. In heterotrophs such as yeasts and fungi growing on carbon-containing media, high-polymeric polyphosphates, localized on the surface and closely connected metabolically with cell-wall biosynthesis and functioning, are most intensively synthesized. In contemporary microorganisms functioning under various conditions, high-polymeric polyphosphates are involved in the regulation of the intracellular levels of free phosphate ions, ATP, ADP, and of pyrophosphate ion balance, biosynthesis, and functioning of biopolymers such as nucleic acids and glycoproteids. Under conditions where adenylate metabolism is repressed, polyphosphates play an important role in the bioenergetics of contemporary microorganisms.