Difference between Escherichia coli O157:H7 and non-pathogenic E. coli: survival and growth in seasonings.

ABSTRACT

We examined the survival and growth of Escherichia coli O157H7 cells incubated with several seasonings, in comparison with those of non-pathogenic E. coli. The cells were incubated at 25 degrees C for 24 h with several concentrations of NaCl, sucrose, soy sauce, worcester sauce and tomato ketchup, and their survival ratios were determined. The E. coli O157H7 strains showed relatively higher survival ratios in 0.5-1.0 M sucrose, 25% soy sauce and 12.5-50% worcester sauce than the non-pathogenic strains, but slightly lower survival ratios in 0.5-2.0 M NaCl. A noteworthy difference between E. coli O157H7 and the non-pathogenic strains was that incubation in the presence of 12.5% soy sauce allowed the growth of E. coli O157H7 strains but reduced the viable cell numbers of non-pathogenic E. coli strains.