Phosphated Milk Adversely Affects Growth, Cellular Morphology, and Fermentative Ability of Lactobacillus bulgaricus

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Abstract
The influence of phosphates on acid production, growth and cellular morphology of 2 strains of L. bulgaricus was examined. Prior growth of these organisms in milk containing 1-2% phosphate or commercial phage inhbitory medium diminished acid production upon transfer to 11% nonfat milk solids. Decreased acid production was a consequence of growth inhibition by the presence of 1-2% phosphate in milk. Concomitant with growth inhibition, the cellular morphology of both L. bulgaricus 1243-F and 1489 was altered by propagation in milk containing 2-3% phosphate or commercial phage inhibitory medium. These organisms, which existed as short bacilloid rods when grown in 11% nonfat milk solids, grew as long chains of connected cells when cultivated in media containing phosphates. This alteration of cellular morphology was not reversed by 1 transfer through 11% nonfat milk solids, and curd formation by cells previously propagated through phosphated milk was affected adversely. The poor growth and alteration of cellular morphology of these organisms when propagated in phosphated milk directly reflect their requirement for Ca, Mn and Mg for proper growth and cell assembly.