title: Effect of immobilization and salt concentration on the growth dynamics of Escherichia coli K12 and Salmonella typhimurium.
abstract: Up to now, it is generally observed that (i) the microbial growth domain is confined by structure-induced stress, or (ii) a solid(-like) environment can enhance microbial survival/growth. In most studies in solid(-like) systems, structure is induced by the addition of gelatin. The aim of this study was to evaluate the effect of other structure-inducing components on the growth dynamics. Both single and binary gel systems are used. Growth is studied when simultaneously exposed to salt stress. Experiments are performed in spectrophotometer tubes, filled with 1 mL of liquid, or structured inoculated brain heart infusion. Four different (combinations of) gelling agents are tested, that is, gelatin, xanthan gum, a 50% combination of xanthan gum and gelatin, and a 50% combination of carrageenan and gelatin. Experiments determine the growth behavior of both Escherichia coli (0% to 0.5% and 1%, 2%, 3%, 4%, and 5% NaCl) and Salmonella Typhimurium (0%, 1%, 2%, 3%, 4%, and 5% NaCl) at 23.5 and 27 °C. By means of plate counting, the growth dynamics are determined. At the studied conditions, growth of E. coli and Salmonella Typhimurium seems independent of the type of structure-inducing component. However, at higher concentrations of salt (>2%), lag phases are typically shorter in solid(-like) systems than in liquid media. For the conditions tested, the effect of a structured environment on growth rate and maximal cell density can be neglected.
authors: Chemical and Biochemical Process Technology and Control (BioTeC), KU Leuven W. de Croylaan 46, B-3001 Leuven, Belgium.
authors: Kathleen
authors: K
authors: Boons
authors: Eva
authors: E
authors: Van Derlinden
authors: Laurence
authors: L
authors: Mertens
authors: Vicky
authors: V
authors: Peeters
authors: Jan F
authors: JF
authors: Van Impe
mesh_terms: D018914:Cells, Immobilized; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D048168:Escherichia coli K12 / Q000187:drug effects / Q000254:growth & development*; D005506:Food Contamination / Q000517:prevention & control; D005516:Food Microbiology; D005780:Gelatin / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D011135:Polysaccharides, Bacterial / Q000737:chemistry; D012486:Salmonella typhimurium / Q000187:drug effects / Q000254:growth & development*; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D011135:Polysaccharides, Bacterial; D012965:Sodium Chloride; D005780:Gelatin; C002563:xanthan gum