Abstract
The effect of sorbic acid in the pH range 4.9 to 7.0 on the probability P of growth of a single vegetative bacterium of proteolytic strains of Clostridium botulinum has been determined by comparison of the most probable number count of the bacteria in media at pH 4.9 to 7.0 containing a series of concentrations of potassium sorbate and in a nutrient medium at pH 6.8 to 7.0. The media were maintained under strictly anaerobic conditions at a redox potential equivalent to lower than -350 mV at pH 7. In medium adjusted to the required pH with HCl, P for strain ZK3 (type A) at pH 5.1 or 5.5 after 2 days at 30 degrees C was similar to that at pH 6.8 to 7.0 but was slightly lower at pH 4.9. Potassium sorbate inhibited growth, the inhibition being a function of the concentration of undissociated sorbic acid. A calculated undissociated sorbic acid concentration of 156 mg/liter delayed growth of strain ZK3 (type A) but did not result in a significant decrease in P after an incubation time of 14 days. Higher concentrations of undissociated sorbic acid caused longer delays before maximum most probable number counts developed, and a calculated undissociated sorbic acid concentration of 282 mg/liter decreased log P for strain ZK3 after an incubation time of 14 days by a factor of 5.5 to 7.5. Four additional type A strains and five type B strains were inhibited to an extent comparable to inhibition of strain ZK3.(ABSTRACT TRUNCATED AT 250 WORDS)
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Blocher J. C., Busta F. F. Multiple modes of inhibition of spore germination and outgrowth by reduced pH and sorbate. J Appl Bacteriol. 1985 Nov;59(5):469–478. doi: 10.1111/j.1365-2672.1985.tb03347.x. [DOI] [PubMed] [Google Scholar]
- EMARD L. O., VAUGHN R. H. Selectivity of sorbic acid media for the catalase negative lactic acid bacteria and clostridia. J Bacteriol. 1952 Apr;63(4):487–494. doi: 10.1128/jb.63.4.487-494.1952. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eklund T. The antimicrobial effect of dissociated and undissociated sorbic acid at different pH levels. J Appl Bacteriol. 1983 Jun;54(3):383–389. doi: 10.1111/j.1365-2672.1983.tb02632.x. [DOI] [PubMed] [Google Scholar]
- Genigeorgis C. A. Factors affecting the probability of growth of pathogenic microorganisms in foods. J Am Vet Med Assoc. 1981 Dec 15;179(12):1410–1417. [PubMed] [Google Scholar]
- Smoot L. A., Pierson M. D. Mechanisms of sorbate inhibition of Bacillus cereus T and Clostridium botulinum 62A spore germination. Appl Environ Microbiol. 1981 Sep;42(3):477–483. doi: 10.1128/aem.42.3.477-483.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stiratelli R., Laird N., Ware J. H. Random-effects models for serial observations with binary response. Biometrics. 1984 Dec;40(4):961–971. [PubMed] [Google Scholar]
- YORK G. K., 2nd, VAUGHN R. H. Use of sorbic acid enrichment media for species of Clostridium. J Bacteriol. 1954 Dec;68(6):739–744. doi: 10.1128/jb.68.6.739-744.1954. [DOI] [PMC free article] [PubMed] [Google Scholar]