title: Distinct effects of sorbic acid and acetic acid on the electrophysiology and metabolism of Bacillus subtilis.
abstract: Sorbic acid and acetic acid are among the weak organic acid preservatives most commonly used to improve the microbiological stability of foods. They have similar pKa values, but sorbic acid is a far more potent preservative. Weak organic acids are most effective at low pH. Under these circumstances, they are assumed to diffuse across the membrane as neutral undissociated acids. We show here that the level of initial intracellular acidification depends on the concentration of undissociated acid and less on the nature of the acid. Recovery of the internal pH depends on the presence of an energy source, but acidification of the cytosol causes a decrease in glucose flux. Furthermore, sorbic acid is a more potent uncoupler of the membrane potential than acetic acid. Together these effects may also slow the rate of ATP synthesis significantly and may thus (partially) explain sorbic acid's effectiveness.
authors.affiliation: Molecular Biology & Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: J W A
authors.initials: JW
authors.lastname: van Beilen
authors.affiliation: Department of Molecular Microbial Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Teixeira de Mattos
authors.affiliation: Department of Molecular Microbial Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: K J
authors.initials: KJ
authors.lastname: Hellingwerf
authors.affiliation: Molecular Biology & Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands s.brul@uva.nl.
authors.forename: S
authors.initials: S
authors.lastname: Brul
mesh_terms: D019342:Acetic Acid / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D004594:Electrophysiology; D005520:Food Preservatives / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013011:Sorbic Acid / Q000494:pharmacology*
chemical_list: D005520:Food Preservatives; D000255:Adenosine Triphosphate; D005947:Glucose; D019342:Acetic Acid; D013011:Sorbic Acid