Survival of Salmonellae on and in tomato plants from the time of inoculation at flowering and early stages of fruit development through fruit ripening

The fate of salmonellae applied to tomato plants was investigated. Five Sal monella serotypes were used to inoculate tomato plants before and after fru its set, either by injecting stems with inoculum or brushing flowers with i t. Ripe tomato fruits were subjected to microbiological analysis. Peptone w ash water, homogenates of stem scar tissues, and homogenates of fruit pulp were serially diluted and plated on bismuth sulfite agar before and after e nrichment. Presumptive Salmonella colonies were confirmed by serological te sts, PCR assay using HILA2 primers, and enterobacterial repetitive intergen ic consensus PCR. Of 30 tomatoes harvested from inoculated plants, 11 (37%) were positive for Salmonella. Of the Salmonella-positive tomatoes, 43 and 40%, respectively, were from plants receiving stem inoculation before and a fter flower set. Two of eight tomatoes produced from inoculated flowers con tained Salmonella. Higher percentages of surface (82%) and stem scar tissue (73%) samples, compared to pulp of Salmonella-positive tomatoes (55%), har bored the pathogen. Of the five serotypes in the inoculum, Montevideo was t he most persistent, being isolated from tomatoes 49 days after inoculation, and Poona was the most dominant, being present in 5 of 11 Salmonella-posit ive tomatoes. Results suggest that Salmonella cells survive in or on tomato fruits from the time of inoculation at flowering through fruit ripening. T omato stems and flowers are possible sites at which Salmonella may attach a nd remain viable during fruit development, thus serving as routes or reserv oirs for contaminating ripened fruit.