Mechanism of Resistance of Saccharomyces bailii to Benzoic, Sorbic and Other Weak Acids Used as Food Preservatives

Abstract

Saccharomyces bailii grows in the presence of high concentrations of sorbic, benzoic and other short‐chain monocarboxylic acids commonly used as preservatives. Starved cells concentrate these acids intracellularly, approximately as expected from the pH of the ceil and the pKa of the acid. On addition of glucose, the intracellular content of preservative is considerably reduced. The glucose effect is sensitive to metabolic inhibitors, and anaerobic respiration is stimulated by the preservatives. The ability to maintain a low intracellular concentration of any of the preservatives tested is induced by growth in the presence of sorbic or benzoic acid and less effectively by butyric or acetic acid. Both induced and uninduced cells are permeable to benzoic and butyric acids. Benzoate and sorbate are not metabolized at a rate significant with respect to the permeation rate. Resistance to these preservatives apparently results primarily from an inducible, energy requiring system which transports preservative from the cell.

Comparison of the inhibitory effect of sorbic acid and amphotericin B on Saccharomyces cerevisiae: is growth inhibition dependent on reduced intracellular pH?

“…Recent evidence also suggests that this energydemanding stress could also be due to the induction of ATPdriven plasma membrane pumps for active extrusion of weak acids from the cell, as first proposed by Warth (1977) recently identified as the Pdrl2 protein is induced by sorbic acid in S. cereoisrae (Piper eral. 1998).…”

Weak acid adaptation: the stress response that confers yeasts with resistance to organic acid food preservatives

“…Nevertheless, Pdr12 action clearly enhances sorbate, benzoate and acetate resistance (Piper et al, 1998 ;Holyoak et al, 1999). Also it has long been known that acid-adapted S. cerevisiae and Z. bailii can maintain an intracellular versus extracellular distribution of benzoate that is not in equilibrium (Warth, 1977(Warth, , 1988(Warth, , 1989Henriques et al, 1997 ;Piper et al, 1998). This indicates the induction of a system whereby adapted cells can reduce their intracellular weak acid pool.…”

Mechanism of inhibitory action of potassium sorbate in Escherichia coli

“…The resistance of S. bailii may be linked to an inducible, energy-requiring system which transports sorbate out of the cell. That property is induced when the yeast has been previously grown in subinhibitory amounts of sorbate (Warth, 1977).…”

“…Detoxification of sorbate by that yeast under aerobic conditions seems to reduce inhibition which varies with medium composition. The addition of cysteine or glutathione to the medium increased the duration and extent of inhibition by retarding the detoxification of sorbate (Deak and Novak, 1968 Pitt, 1974;Pitt and Richardson, 1973;Restaino et al, 1983;Restaino et al, 1982;Warth, 1977).…”

“…bailii becomes resistant to high concentrations of sorbate or benzoate after being preconditioned to growth in moderate amounts of those preservatives (Warth, 1977). Starved cells concentrate the preservatives intracellularly but upon the addition of glucose to the growth medium, the intracellular concentrations of the preservatives are reduced.…”