Influence of acid adaptation on the tolerance of Escherichia coli O157:H7 to some subsequent stresses.
Three stains of Escherichia coli O157:H7, including ATCC 43889, ATCC 43895, and 933, were first subjected to acid adaptation at a pH of 5.0 for 4 h. Thermal tolerance at 52 degrees C and survival of the acid-adapted as well as the nonadapted cells of E. coli O157:H7 in the presence of 10% sodium chloride, 0.85% bile salt, or 15.0% ethanol were investigated. Results showed that the effect of acid adaptation on the survival of E. coli O157:H7 varied with the strains and types of subsequent stress. Acid adaptation caused an increase in the thermal tolerance of E. coli O157:H7 ATCC 43889 and ATCC 43895, but no significant difference in the thermal tolerance was noted between acid-adapted and nonadapted cells of E. coli O157:H7 933. Although the magnitude of increase varied with strains of test organisms, acid adaptation generally led to an increase in the tolerance of E. coli O157:H7 to sodium chloride. On the other hand, the susceptibility of acid-adapted cells of the three strains of E. coli O157:H7 tested did not show a significant difference from that of their nonadapted counterparts when stressed with bile salt. The acid-adapted cells of E. coli O157:H7 ATCC 43889 and ATCC 43895 were less tolerant than the nonadapted cells to ethanol, whereas the tolerance of adapted and nonadapted cells of E. coli O157:H7 933 showed no significant differences.
Cheng
Hsin-Yi
HY
Graduate Institute of Food Science and Technology, National Taiwan University, Taipei.
Yang
Hsin-Yi
HY
Chou
Cheng-Chun
CC
D000222:Adaptation, Physiological; D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001647:Bile Acids and Salts / Q000494:pharmacology; D019453:Escherichia coli O157 / Q000254:growth & development / Q000502:physiology*; D000431:Ethanol / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors
D000891:Anti-Infective Agents, Local; D001647:Bile Acids and Salts; D000431:Ethanol; D012965:Sodium Chloride