Isolation of polyphosphate-accumulating lactic acid bacteria from natural whey starters

Natural water-buffalo whey starters are used in the manufacture of Mozzarella cheese in Southern Italy. Microscopic examination of 12 commercial whey starters revealed high concentrations of lactic acid bacteria, in particular lactobacilli, containing inclusion bodies. Differential staining techniques revealed that the inclusion bodies contained high concentrations of polyphosphate (polyP). Because of the potential role of polyP in intracellular pH control, the presence of this polymer in starter bacteria may be an environmental adaptation to the typical high acidity storage conditions of natural starters.