Polyphosphate in Lactic Acid Bacteria: A Functional Molecule for Food and Health Applications

The linear polymer polyphosphate (polyP) is found across all three domains of life and fulfills diverse physiological functions, including phosphorus storage, chaperone activity and stress tolerance. In bacteria, polyP synthesis is catalyzed by polyphosphate kinase (Ppk), while its degradation is carried out by exopolyphosphatases (Ppx). The intracellular polyP level is determined by the balance between these two enzymatic activities; however, the regulatory mechanisms governing this balance remain incompletely understood. In higher eukaryotes, polyP participates in a wide variety of physiological processes. In relation to this, accumulating evidence suggests that polyP may also confer beneficial effects on human intestinal health, triggering increased interest in the production of polyP by probiotic lactic acid bacteria. This review summarizes the current knowledge on polyP metabolism in these bacteria and explores its functional properties and potential applications.