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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Stratford, Malcolm Nebe-von-Caron, Gerhard Steels, Hazel Novodvorska, Michaela Ueckert, Joerg Archer, David B. |
| Description | Country affiliation: United kingdom Author Affiliation: Stratford M ( School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom. malcolm.stratford@nottingham.ac.uk) |
| Abstract | Weak-acid preservatives commonly used to prevent fungal spoilage of low pH foods include sorbic and acetic acids. The 'classical weak-acid theory' proposes that weak acids inhibit spoilage organisms by diffusion of undissociated acids through the membrane, dissociation within the cell to protons and anions, and consequent acidification of the cytoplasm. Results from 25 strains of Saccharomyces cerevisiae confirmed inhibition by acetic acid at a molar concentration 42 times higher than sorbic acid, in contradiction of the weak-acid theory where all acids of equal pK(a) should inhibit at equimolar concentrations. Flow cytometry showed that the intracellular pH fell to pH 4.7 at the growth-inhibitory concentration of acetic acid, whereas at the inhibitory concentration of sorbic acid, the pH only fell to pH 6.3. The plasma membrane Hâº-ATPase proton pump (Pma1p) was strongly inhibited by sorbic acid at the growth-inhibitory concentration, but was stimulated by acetic acid. The Hâº-ATPase was also inhibited by lower sorbic acid concentrations, but later showed recovery and elevated activity if the sorbic acid was removed. Levels of PMA1 transcripts increased briefly following sorbic acid addition, but soon returned to normal levels. It was concluded that acetic acid inhibition of S. cerevisiae was due to intracellular acidification, in accord with the 'classical weak-acid theory'. Sorbic acid, however, appeared to be a membrane-active antimicrobial compound, with the plasma membrane Hâº-ATPase proton pump being a primary target of inhibition. Understanding the mechanism of action of sorbic acid will hopefully lead to improved methods of food preservation. |
| File Format | HTM / HTML |
| ISSN | 01681605 |
| Issue Number | 3 |
| Volume Number | 161 |
| e-ISSN | 18793460 |
| Journal | International Journal of Food Microbiology |
| Language | English |
| Publisher | Elsevier |
| Publisher Date | 2013-02-15 |
| Publisher Place | Netherlands |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | Protons Research Support, Non-u.s. Gov't Discipline Microbiology Saccharomyces Cerevisiae Proteins Pharmacology Metabolism Journal Article Saccharomyces Cerevisiae Food Preservation Microbial Sensitivity Tests Acetic Acid Proton-translocating Atpases Genetics Food Preservatives Hydrogen-ion Concentration Discipline Nutritional Sciences Sorbic Acid |
| Content Type | Text |
| Resource Type | Article |
| Subject | Medicine Microbiology Safety, Risk, Reliability and Quality Food Science |
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