Effect of three preservatives on the growth of Bacillus cereus, Vero cytotoxigenic Escherichia coli and Staphylococcus aureus, on plates with gradients of pH and sodium chloride concentration.
The effect of temperature, pH, sodium chloride concentration and a preservative (sodium benzoate, sodium nitrite or potassium sorbate) on the growth of three foodborne bacterial pathogens (Bacillus cereus, Vero cytotoxigenic Escherichia coli and Staphylococcus aureus) was studied using gradient gel plates. Growth, expressed in optical density units, was recorded using image analysis techniques, and was expressed as three-dimensional grids. These gave a visual indication of the effects of any three of the environmental factors on bacterial proliferation. Sorbate was completely effective against E. coli at all temperature/pH/NaCl combinations, and was the most effective preservative tested against B. cereus. Increase in the acidity and/or the NaCl concentration improved the effect of all the preservatives, except nitrite when used against St. aureus. Nitrite was the least effective preservative, particularly against St. aureus. At < 25 degrees C, sorbate was more effective than benzoate against St. aureus when used with higher concentrations of NaCl. At 35 degrees C benzoate was the most effective preservative against St. aureus, especially when used at pH < 6.
Thomas
L V
LV
School of Pure and Applied Biology, University of Wales, College of Cardiff, UK.
Wimpenny
J W
JW
Davis
J G
JG
D001409:Bacillus cereus / Q000187:drug effects* / Q000254:growth & development; D001427:Bacterial Toxins / Q000096:biosynthesis; D001431:Bacteriological Techniques; D001565:Benzoates / Q000494:pharmacology; D019817:Benzoic Acid; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D005069:Evaluation Studies as Topic; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005520:Food Preservatives / Q000494:pharmacology*; D005517:Foodborne Diseases / Q000517:prevention & control; D006863:Hydrogen-Ion Concentration; D022622:Shiga Toxin 1; D012965:Sodium Chloride; D012977:Sodium Nitrite / Q000494:pharmacology; D013011:Sorbic Acid / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D013696:Temperature
D001427:Bacterial Toxins; D001565:Benzoates; D005520:Food Preservatives; D022622:Shiga Toxin 1; D012965:Sodium Chloride; D019817:Benzoic Acid; D012977:Sodium Nitrite; D013011:Sorbic Acid