Effect of Temperature, pH and Sodium Chloride Concentrations on Production of Staphylococcal Enterotoxins A and B

Staphylococcus aureus strain S-6 was used to produce enterotoxins A (SEA) and B (SEB) by the sac culture technique using casein hydrolysate medium, NZ-Amine NAK, enriched with thiamine and niacin, under the following conditions: incubation temperatures of 20 to 45 °C, pH values of 4.5 to 9.0 and NaCl concentrations of 0 to 125%. The highest enterotoxin production was obtained at the optium growth conditions, 39.4°C and pH 7.0. Production of the two enterotoxins was completely inhibited at 20°C, above 45°C, at pH 4.5 and by 12% NaCl. Increases in the NaCl concentration resulted in a decrease in enterotoxin production, with a more pronounced effect on SEB production than on SEA production. Production of the enterotoxins in 4% NaCl was not observed at pH 6.0 and 6.5 after 18 h of incubation at 37°C. The results show no major differences with those obtained using a different strain for each toxin, indicating that the behavior is inherent to the specific enterotoxin and not to the strain that produces it.