Further Observations on the Relation of pH Value to Toxicity of Preservatives to Microörganisms

Cruess, W. V.; Irish, Julie

doi:10.1128/jb.23.2.163-166.1932

Cited by 18 publications

(11 citation statements)

References 1 publication

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“…3B) was sensitive to both short (C2 to C6)and long (012 to C16)-chain fatty acids. The IC50 concentrations for each fatty acid were similar to those observed for N. gonorrhoeae CS-7 and decreased with increasing chain length to a minimum of 5 ,lM for myristic (tetradecanoic; C04) acid. Palmitic acid (C16) was significantly less inhibitory for B. subtilis (IC50 = 120 ,uM) than for N. gonorrhoeae (IC50 = 5.8 ,uM); stearic acid (C18) was not inhibitory.…”

Section: Resultssupporting

confidence: 68%

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Inhibitory Action of Fatty Acids on the Growth of Neisseria gonorrhoeae

1977

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Fatty acids of various chain lengths (C1 to C24) were examined for their effects on growth, oxygen consumption, and in vitro reduced nicotinamide adenine dinucleotide oxidase activity ofNeisseria gonorrhoeae CS-7. The growth inhibition caused by saturated fatty acids increased with increasing chain length to a maximum with palmitic acid (C16). Stearic acid (C18) and longer saturated fatty acids showed little inhibition of growth. However, unsaturated fatty acids of chain length C16 to C20 were inhibitory. Similar inhibition was observed with Bacillus subtilis and a deep rough mutant of Salmonella typhimurium. Wildtype S. typhimurium and Pseudomonas aeruginosa were more resistant to medium-chain (C7 to C1o) fatty acids and completely resistant to long-chain (C12 to C18) fatty acids. Thus, sensitivity ofN. gonorrhoeae to long-chain fatty acids appears to be related to the permeability of the outer membrane. Growth inhibition by short-chain (C1 to C6) fatty acids was pH dependent; inhibition of growth increased with decreasing pH. Saturated fatty acids inhibited oxygen consumption by log-phase cells of N. gonorrhoeae. This inhibition increased with increasing chain length to a maximum observed with myristic acid (C14). Whereas stearic acid (C18) had little effect upon oxygen consumption, unsaturated C18 fatty acids were inhibitory. An in vitro inhibition of reduced nicotinamide adenine dinucleotide oxidase activity by saturated (C1 to C12) and unsaturated (C16 to C20) fatty acids was also observed. Although the inhibitory concentrations were generally higher than those required to inhibit growth or oxygen consumption, an inhibition ofelectron transport may be partially responsible for the observed growth inhibition. MATERIALS AND METHODS Organisms. N. gonorrhoeae CS-7 (type 4), Salmonella typhimurium DB-21, S. typhimurium TA1535, and Pseudomonas aeruginosa PS-7 have been previously described (30, 32, 34). These organisms were maintained as previously described (30, 32). Bacillus subtilis was obtained from the culture collection of the

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Section: Resultssupporting

confidence: 68%

“…The effect of pH on inhibition by short-chain fatty acids has been reported by several authors (5,19,20,26,38) who found that inhibitory activity increases as the pH is lowered. This observation has led to the conclusion that the undissociated molecules are responsible for toxicity (12,19,26).…”

Section: Discussionmentioning

confidence: 79%

Inhibitory Action of Fatty Acids on the Growth of Neisseria gonorrhoeae

1977

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“…Our data confirm antilisterial effects of sodium diacetate and demonstrate sensitivity of other foodborne bacteria to the compound, including an enterohemorrhagic E. coli strain. These observations, although based on a limited number of microorganisms, confirm sensitivity of bacteria to acetates (Eklund 1989), and suggest that Gram-negative bacteria may be more sensitive than the Gram-positive. Suppressed numbers of total aerobes and extended shelf life were observed by 0.3% sodium diacetate in fresh beef but addition of the compound to broth or meat lowered the pH.…”

Section: Resultssupporting

confidence: 53%

“…For example, inhibition of mold growth at pH 5.8 required twice as much acetic acid as required at pH 5 5 . 0 (Cruess and Irish 1932;Kirby ec al. 1937).…”

Section: Introductionmentioning

confidence: 99%

INHIBITION OF LISTERIA MONOCYTOGENES AND OTHER BACTERIA BY SODIUM DIACETATE

Shelef

Addala

1994

Journal of Food Safety

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Growth and survival patterns of Listeria monocytogenes strain Scott A were studied in brain heart infusion broth containing sodium diacetate. Minimum inhibitory concentrations decreased with decrease in temperature, from 35 and 32 mM at 35C and 20C, respectively, to 28 mM at 5C. Broth pH containing 35, 32, and 28 mM sodium diacetate was 5.25, 5.40 and 5.60, respectively. Sodium diacetate was more effective than acetic acid alone in inhibiting the organism over the pH range of 5.0‐6.0. Addition of 21 mM (0.3%) sodium diacetate to ground beef or beef slurry suppressed total aerobic counts during refrigerated storage. Although the meat pH decreased from 5.6 to 5.2 by the addition of the compound, a major part of the antimicrobial effect was attributed to the diacetate and not just pH. Sodium diacetate suppressed growth of three additional L. monocytogenes strains and strains of Escherichia coli, Pseudomonas fluorescens, Salmonella enteriditis and Shewanella putrefaciens. P. fragi, Yersinia enterocolitica, Enterococcus faecalis, Lactobacillus fermentis and Staphylococcus aureus were insensitive to the compound. Sodium diacetate has potential for use in controlling growth of listeriae in meat, poultry and fish products and suppressing growth of certain Gram‐negative spoilage and pathogenic microorganisms.

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“…It has long been known that weak acids acting as inhibitors of microbial growth show a clear pH dependency, being less effective as pH increases (Cruess & Richert 1929;Cruess & Irish 1932;Hoffman et al 1941, Simon & Blackman 1949). Simon & Blackman (1949) reviewed earlier work showing this pH dependency, and noted that authors often failed to calculate the concentration of undissociated acid present at inhibitory conditions: 'Hence it is not surprising that the view should be widely held that the undissociated molecule is the only toxic form of a weak acid or base.'…”

mentioning

confidence: 99%

The antimicrobial effect of dissociated and undissociated sorbic acid at different pH levels

Eklund¹

1983

Journal of Applied Bacteriology

296

159

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The minimum inhibitory concentration of sorbic acid has been determined for Bacillus subtilis, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. The inhibition was shown to be due to both undissociated and dissociated acid, and the effect of each has been calculated in accordance with a proposed mathematical model. Although the inhibitory action of undissociated acid was 10-600 times greater than that of dissociated acid, the latter caused more than 50% of the growth inhibition at pH levels above 6 for most of the organisms tested.

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Further Observations on the Relation of pH Value to Toxicity of Preservatives to Microörganisms

Cited by 18 publications

References 1 publication

Inhibitory Action of Fatty Acids on the Growth of Neisseria gonorrhoeae

Inhibitory Action of Fatty Acids on the Growth of Neisseria gonorrhoeae

INHIBITION OF LISTERIA MONOCYTOGENES AND OTHER BACTERIA BY SODIUM DIACETATE

The antimicrobial effect of dissociated and undissociated sorbic acid at different pH levels

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