Variability in growth/no growth boundaries of 188 different Escherichia coli strains reveals that approximately 75 % have a higher growth probability under low pH conditions than E. coli O157:H7 strain ATCC 43888. (February 2015)

• Record Type: Journal Article
• Authors: Haberbeck, L.U.; Oliveira, R.C.; Vivijs, B.; Wenseleers, T.; Aertsen, A.; Michiels, C.; Geeraerd, A.H.
• Is Part Of: Food microbiology. Volume 45:Part B(2015)
• Page Start: 222
• Page End: 230
• Publication Date: 2015-02
• Subjects: Escherichia coli -- Strains variability -- Growth/no growth boundary -- Logistic regression -- Generalized linear mixed model; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2014.06.024
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: This study investigated the variation in growth/no 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 °C). 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 growth/no 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. E. 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. Highlights: A growth/no growth study with 188 Escherichia coli strains. A purposeful selection to identify significant variables for logistic regression. A generalized linear mixed model to compare the growth responses of E. coli strains. In more stressful conditions, 75% of the strains grew significantly better than O157:H7 (ATCC 43888).