title: 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.
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.
authors.affiliation: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium; MEBIOS-Division of Mechatronics, Biostatistics and Sensors, Department of Biosystems (BIOSYST), KU Leuven, W. de Croylaan 42, B-3001 Leuven, Belgium. Electronic address: leticia.haberbeck@kuleuven.be.
authors.forename: L U
authors.initials: LU
authors.lastname: Haberbeck
authors.affiliation: Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Naamsestraat 59-Box 2466, 3000 Leuven, Belgium.
authors.forename: R C
authors.initials: RC
authors.lastname: Oliveira
authors.affiliation: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Vivijs
authors.affiliation: Laboratory of Socioecology and Social Evolution, Zoological Institute, KU Leuven, Naamsestraat 59-Box 2466, 3000 Leuven, Belgium.
authors.forename: T
authors.initials: T
authors.lastname: Wenseleers
authors.affiliation: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Aertsen
authors.affiliation: Laboratory of Food Microbiology, KU Leuven, Kasteelpark Arenberg 22, B-3001 Leuven, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Michiels
authors.affiliation: MEBIOS-Division of Mechatronics, Biostatistics and Sensors, Department of Biosystems (BIOSYST), KU Leuven, W. de Croylaan 42, B-3001 Leuven, Belgium. Electronic address: Annemie.Geeraerd@kuleuven.be.
authors.forename: A H
authors.initials: AH
authors.lastname: Geeraerd
mesh_terms: D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000737:chemistry / Q000145:classification / Q000254:growth & development*; D019453:Escherichia coli O157 / Q000737:chemistry / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration; D016015:Logistic Models; D008962:Models, Theoretical; D013696:Temperature
keywords: Escherichia coli; Generalized linear mixed model; Growth/no growth boundary; Logistic regression; Strains variability