Growth inhibition of putrefactive anaerobe 3679 caused by stringent-type response induced by protonophoric activity of sorbic acid

Abstract

The inhibitory effects of potassium sorbate on the bioenergetics, phenylalanine uptake, protein synthesis, and certain aspects of cell regulation were examined in putrefactive anaerobe 3679. Undissociated sorbic acid appeared to act as a protonophore by lowering the intracellular pH and dissipating the proton motive force of the membrane. Sorbate inhibited the uptake of phenylalanine, decreased the rate of protein synthesis, and altered patterns of phosphorylated nucleotide accumulation, resulting in increased intracellular concentrations of GTP, ppGpp, and an unidentified compound (possibly pppGpp). The addition of a noninhibitory amount of tetracycline released the inhibition of growth by sorbate. Based on these results, we concluded that the inhibition of putrefactive anaerobe 3679 by sorbate resulted from a stringent-type regulatory response induced by the protonophoric activity of sorbic acid.

Modelling the behaviour of Listeria monocytogenes in ground pork as a function of pH, water activity, nature and concentration of organic acid salts

“…Additional toxic effect of acetic acid on cells by modification of physiological and metabolic activities was also demonstrated (Eifert et al 1997;Jensen et al 2003). Even if the mechanism of action of potassium sorbate has remained uncertain, it is partly based on its ability to inhibit the amino acid uptake in Penicillium chrysogenum and in vesicles of some bacteria (Ronning and Hilmer 1987). Our results confirmed that organic acid salts did not have the same inhibitory effect according to their nature.…”

“…2003). Even if the mechanism of action of potassium sorbate has remained uncertain, it is partly based on its ability to inhibit the amino acid uptake in Penicillium chrysogenum and in vesicles of some bacteria (Ronning and Hilmer 1987).…”

Bacterial spores and chemical sporicidal agents.

“…Disinfectant-induced structural changes in fully developed spores have been described (123,168,189), but these have not been fully related to their biochemical effects on sporulating cells. Thus, the mechanism of action (see later section) of many sporicidal agents is still often poorly described.…”

“…Several antibacterial agents are known to inhibit germination. These include alcohols, aldehydes, phenols and cresols, parabens, sorbic acid, and mercuric chloride (2,3,47,66,68,100,128,148,149,156,166,168,171,172,181,190,193,195,198,219,220,223,234; B. M. Lund, Ph.D. dissertation, University of London, London, England, 1962). This inhibition (Table 10) occurs at concentrations that are closely related to those that inhibit the growth of vegetative bacteria.…”

“…Methyl and propyl parabens are commonly used in the food industry as preservatives, with the propyl ester more effective in inhibiting C. botulinum growth and toxin production (171). Sorbic acid is a weak lipophilic acid widely used as a food preservative (127,168); it inhibits botulinal spore germination (there being a loss of heat resistance), a property that is pH dependent and appears at pH values of <6 (165,196,197). Potassium sorbate delays C. botulinum growth and toxin production in cured meats (64) and, when added to acidic foods, is hydrolyzed to sorbic acid.…”