soil management on movement of Salmonella enterica Typhimurium
in tomato plants . In the first phase, individual leaflets of 84 tomato plants
grown in conventional or organic soils were dip inoculated two to four
times before fruiting with either of two Salmonella Typhimurium strains
(109 CFU/ml; 0.025% [vol/vol] Silwet L-77). Inoculated and adjacent
leaflets were tested for Salmonella spp. densities for 30 days after each
inoculation. Endophytic bacterial communities were characterized by
polymerase chain reaction denaturing gradient gel electrophoresis before
and after inoculation. Fruit and seed were examined for Salmonella spp.
incidence. In phase 2, extracted seed were planted in conventional soil,
and contamination of leaves and fruit of the second generation was
checked. More Salmonella spp. survived in inoculated leaves on plants
grown in conventional than in organic soil. The soil management effect
on Salmonella spp. survival was confirmed for tomato plants grown in
two additional pairs of soils. Endophytic bacterial diversities of tomato
plants grown in conventional soils were significantly lower than those in
organic soils. All contaminated fruit (1%) were from tomato plants grown
in conventional soil. Approximately 5% of the seed from infested fruit
were internally contaminated. No Salmonella sp. was detected in plants
grown from contaminated seed