Combined effects of pH (4.5-7.4) and water activity (
aw, 0.99-0.88) on the growth and enterotoxin production by five Staphylococcal strains 100, S-6, 361, K858 and T7436, producing enterotoxins A, B, C, AB, and AC, respectively, were studied in Brain Heart Infusion broth for 48hr. At 35C, Staphylococcal enterotoxin A (SEA) was produced at
aw>0.92 or at pH>4.5, but no SEA was produced at
aw 0.92 and pH 5.3. SEB and SEC were produced at
aw>0.96 and pH>5.3 and
aw>0.96 and pH>4.5, respectively. No SEB was produced at
aw 0.96 and pH 5.3. No growth occurred at
aw<0.92 and pH 4.5. The enterotoxin production changed depending on the interaction of these factors. SEA production was much less affected by
aw and pH than was SEB and SEC. The enterotoxin production by the strains K858 and T7436 producing respectively SEA plus SEB and SEA plus SEC were both affected.
View full abstract