Ionic and Energetic Changes at Competence in the Naturally Transformable Bacterium Streptococcus pneumoniae

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Abstract
Addition of competence factor extracts to trigger competence in a culture of Streptococcus pneumoniae induced an increase in the intracellular pH and the Na+ content of the bacteria without any change in the K+ pool in the membrane potential. These ionic shifts were concomitant with a stimulation of glycolysis that resulted in an enhanced ATP pool. Thus, in transforming conditions, at extracellular pH 7.8, competent bacteria presented a particularly high energetic state resulting from an increase in .DELTA.pH and in the ATP pool, associated with an enhanced Na+ content. These features are discussed in the context of homeostasis regulation in response to an environmental stimulus.