Variability in growtho growth boundaries of 188 different Escherichia coli strains reveals that approximately 75 % have a higher growth probability under low pH conditions than E. coli 0157:H7 strain ATCC 43888

摘要

This study investigated the variation in growtho growth boundaries of 188 Escherichia coli strains. Experiments were conducted in Luria-Bertani media under 36 combinations of lactic acid (LA) (0 and 25 mM), pH (3.8,3.9, 4.0,4.1,4.2 and 4.3 for 0 mM LA and 4.3,4.4,4.5,4.6, 4.7 and 4.8 for 25 mM LA) and temperature (20, 25 and 30 ℃). After 3 days of incubation, growth was monitored through optical density measurements. For each strain, a so-called purposeful selection approach was used to fit a logistic regression model that adequately predicted the likelihood for growth. Further, to assess the growtho growth variability for all the strains at once, a generalized linear mixed model was fitted to the data. Strain was fitted as a fixed factor and replicate as a random blocking factor. £. coli O157:H7 strain ATCC 43888 was used as reference strain allowing a comparison with the other strains. Out of the 188 strains tested, 140 strains (-75%) presented a significantly higher probability of growth under low pH conditions than the O157:H7 strain ATCC 43888, whereas 20 strains (-11%) showed a significantly lower probability of growth under high pH conditions.