Internal pH and Acid Anion Accumulation in and Exposed to Lactic or Acetic Acids at Mildly Acidic pH.

Organic acids are widely employed in the food industry to control growth of microbial pathogens such as and There is substantial evidence that intracellular accumulation of acid anions is a major inhibitor to cell viability, and that some bacteria are able to combat the toxic effects of anion accumulation their ability to continue active metabolism at a lower intracellular pH (pH). This study followed the accumulation of acid anion into the cell pellet and parallel changes in pH in two human pathogenic strains of (N1-227 and R2-499) and in O157:H7 after exposure to sub-bacteriostatic levels of lactic and acetic acids at mildly acidic pH 6. The methodology employed in these studies included independent measures of pH and intracellular anion accumulation.