Korea University Food Microbiology Laboratory

Changes in heat tolerance of Escherichia coli O157H7 after exposure to acidic environments
Year of publication 2004년 이전
Author Ryu, J.H., & L. R. Beuchat.
Publication in journal Food Microbiology, 1999, 16, 317−324
Status of publication Published


 Acid-adapted bacterial cells are known to have enhanced tolerance to various secondary stresses.  However, a comparison of heat tolerance of acid-adapted and acid-shocked cells of Escherichia coli O157:H7 has not been reported. D- and z-values of acid-adapted, acid-shocked, and control cells of an unusually heat-resistant strain (E0139) of E. coli O157:H7, as well as two other strains of E. coli O157:H7, were determined based upon the number of cells surviving heat treatment at 52, 54 or 56°C  in tryptic soy broth (pH 7.2) for 0,10, 20 or 30 min. The unusual heat tolerance of  E. coli O157:H7 strain  E0139 was confirmed. D-values for cells from 24-h cultures wer100.2, 28.3, and 6.1 min at 52, 54 and 56°C, respectively, with a z-value of 3 3°C. The highest D-values of other E. coli O157:H7 strains were 13.6 and 9.2 min at 52 and 54°C, respectively, whereas highest D-values of non-O157:H7 st