Ecological, physiological and genetic factors associated with the survival and growth of Salmonella on or within tomatoes

The persistence of different Salmonella entericia serovars on/within pre- and post harvest tomatoes was investigated. The results showed that persistence of Salmonella on preharvest tomatoes was serovar dependent with those implicated in previous tomato implicated outbreaks (e.g. Montevideo) persisting to a greater extent than those associated with foods of animal origin (e.g. Typhimurium). Although variation in attachment strength, bioflm formation, cellulose production and rpoS activity was found between serovars none of the attributes could be correlated to persistence on tomatoes. Microecology studies of tomatoes at pre- and post-harvest demonstrated that microflora associated with Salmonella contaminated fruit differed to that associated with non-inoculated controls. The results from the current study would suggest that Salmonella populations were either positively or negatively affected by the presence of Bacillus spp. The implications of the results on the microbiological safety of tomatoes are discussed.