Submitted to: International Association for Food Protection
Publication Type: Other
Publication Acceptance Date: March 15, 2002
Publication Date: July 1, 2002
Citation: OSCAR, T.P. GROWTH KINETICS OF PARENT AND GREEN FLUORESCENT PROTEIN-PRODUCING STRAINS OF SALMONELLA. INTERNATIONAL ASSOCIATION FOR FOOD PROTECTION. 2002. p. 119. Technical Abstract: The green fluorescent protein (GFP) from the jellyfish Aequorea victoria can be expressed in and used to follow the fate of Salmonella in microbiologically complex ecosystems, such as food. As a first step in evaluating GFP as a tool for the development of predictive models for naturally contaminated food, the current study was undertaken to compare the growth kinetics of parent and GFP-producing strains of Salmonella. Growth kinetics of stationary phase cells of parent and GFP strains of Salmonella Enteritidis, S. Typhimurium and S. Dublin were compared using a previously established sterile chicken burger model system. Growth curves, which were conducted at constant temperatures from 10 to 48 C, were fit to a three-phase linear model to determine lag time, specific growth rate and maximum population density. Secondary models for the growth parameters as a function of temperature were generated and compared between the parent and GFP strain pairs. Effects of GFP on the three growth parameters were significant (P<0.05) and were affected by serotype and incubation temperature. Expression of GFP reduced specific growth rate and maximum population density while having only a small effect on lag time of the three serotypes. The optimum specific growth rate was reduced by 0.2 log CFU per h, whereas the maximum population density was reduced by 1 to 1.5 log cycles. Results indicated that the GFP strains had different growth kinetics than the parent strains and thus, would not be good marker strains for developing predictive models for naturally contaminated food.