Susceptibility of the rabbit enteropathogenic strain Escherichia coli C6 (O128 serogroup) to C6-C14 fatty acids, oleic, citric, lactic and fumaric acid at 5 mg/mL was determined by the plating technique in the near-neutral pH region (pH approximately 6.5), and in a weakly acid and acid environment (pH 5.4 +/- 0.1 and 2.2-2.5, respectively). In the near-neutral pH region caproic and caprylic acid reduced the concentration of viable cells by 3 and 6 orders, respectively. At lower pH the bactericidal effect of caproic acid remained similar, but caprylic acid decreased the concentration of viable cells to < 100/mL. The bactericidal activity of capric acid was low at pH 6.5 but increased at pH 5.3. High environmental acidity was intrinsically bactericidal and at very low pH the effects of fatty acids were thus less pronounced. Citric acid reduced the counts of viable cells to 1/10. Antimicrobial activity of other acids examined was marginal or absent. Medium-chain fatty acids, caprylic and, to a lesser extent, also caproic and capric acid were better antimicrobials than other organic acids examined; the antimicrobial activity of fatty acids toward the C6 strain was pH-dependent. Beneficial effects of citric, lactic and fumaric acid reported by animal nutritionists are thus probably related to factors other than their direct antimicrobial action.

• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Escherichia coli drug effects   growth & development   MeSH
• Escherichia coli Infections microbiology   veterinary   MeSH
• Caprylates pharmacology   MeSH
• Hydrogen-Ion Concentration MeSH
• Rabbits MeSH
• Citric Acid pharmacology   MeSH
• Carboxylic Acids pharmacology   MeSH
• Fatty Acids pharmacology   MeSH
• Microbial Sensitivity Tests MeSH
• Organic Chemicals pharmacology   MeSH
• Colony Count, Microbial MeSH
• Animals MeSH
• Check Tag
• Rabbits MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Caprylates MeSH
• Citric Acid MeSH
• Carboxylic Acids MeSH
• Fatty Acids MeSH
• octanoic acid MeSH Browser
• Organic Chemicals MeSH

The addition of 100-300 mmol/L of acetic, propionic, butyric or lactic acids (short-chain acids), or of acetic, propionic, and butyric acids (volatile fatty acids, VFA) mixtures increased the degradation of carboxymethyl cellulose (CMC) by R. albus (7.5 to 46 and 6 to 39 %, respectively). Differences among individual acids were observed at 300 mmol/L whereas VFA mixtures differed at 100 mmol/L. When assayed at the same concentration, CMCase activity was increased less by NaCl than by the short-chain acids, whereas ethylene glycol decreased the activity. Since osmolarity and/or ionic strength changes in the medium cannot completely account for the observed increases of carboxymethylcellulase (CMCase) activity, it is suggested that the anions of short-chain acids produce changes in the reaction media polarity that contribute to the effects observed. Alterations in the media could also bring about conformational changes in CMCase leading to increased rates of reaction and subsequent increases in CMC degradation. Finally, explanations for the observed phenomena based on the direct effect of the compounds tested on the cellulosome complex, its domains, and/or its component enzymes are proposed.

• MeSH
• Acetates pharmacology   MeSH
• Rumen microbiology   MeSH
• Butyrates pharmacology   MeSH
• Cellulase metabolism   MeSH
• Sodium Chloride pharmacology   MeSH
• Propionates pharmacology   MeSH
• Ruminococcus enzymology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Acetates MeSH
• Butyrates MeSH
• carboxymethylcellulase MeSH Browser
• Cellulase MeSH
• Sodium Chloride MeSH
• Propionates MeSH

The susceptibility of Salmonella spp. to 15 fatty acids was determined in vitro in cultures grown on glucose. Antimicrobial activity was expressed as IC50 (a concentration at which only 50% of the initial glucose in cultures was utilized). Caprylic acid was the only acid inhibiting glucose utilization. In cultures of S. enteritidis, S. infantis and S. typhimurium, IC50 of caprylic acid ranged from 0.75 to 1.17 mg/mL. A moderate adaptation effect was observed as these values increased 1.5-1.8 times when bacteria were subcultured 10 times in media containing a low concentration of caprylic acid (1/3 IC50). No effect of calcium ions added in excess on antimicrobial activity of caprylic acid was observed. Incubation of salmonellas with caprylic acid (1 mg/mL; 30 min) at pH 5.2-5.3 led to a reduction in the concentration of viable cells below the detection limit; 2-6% of Salmonella cells survived at pH 6.3-6.6.

• MeSH
• Anti-Bacterial Agents chemistry   pharmacology   MeSH
• Time Factors MeSH
• Adaptation, Physiological MeSH
• Glucose metabolism   MeSH
• Caprylates pharmacology   MeSH
• Hydrogen-Ion Concentration MeSH
• Fatty Acids chemistry   pharmacology   MeSH
• Microbial Sensitivity Tests MeSH
• Colony Count, Microbial MeSH
• Salmonella enteritidis drug effects   growth & development   metabolism   MeSH
• Salmonella typhimurium drug effects   growth & development   metabolism   MeSH
• Salmonella drug effects   growth & development   metabolism   MeSH
• Drug Tolerance MeSH
• Calcium pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Glucose MeSH
• Caprylates MeSH
• Fatty Acids MeSH
• octanoic acid MeSH Browser
• Calcium MeSH