Use of phyllospere associated lactic acid bacteria as biocontrol agents to reduce Salmonella enterica growth on fresh produce

Aims: To identify phyllosphere associated lactic acid bacteria (PLAB) capable of growing and persisting on fresh produce and prevent the growth of pathogenic bacteria such as Salmonella enterica. Methods and Results: We isolated PLAB from fresh produce by washing the produce in PBS + 0.05% tween 80 for 1 hr shaking. The produce was removed and the liquid was plated onto de Man, Rogosa, Sharp agar and incubated at 30^oC for 24 hrs. Isolates were screened for the ability to inhibit the growth of Salmonella enterica pGFP in a high throughput, in vitro fluorescent assay. Isolates that inhibited the growth of S. enterica were assayed for the ability to grow and persist on cantaloupe rinds. Isolates that were able to persist were coated onto cantaloupes and assayed for the ability to inhibit the growth of S. enterica. We isolated two PLAB that inhibited the fluorescence of S. enterica pGFP by 38.4- and 47.2-fold, respectively; were able to grow and persist on the surfaces of cantaloupe melons by over 5×10⁴ CFU cm^-1; and inhibited the growth of S. enterica on the surfaces of cantaloupes by over 3 logs as compared to uninoculated melons. Conclusions: Our PLAB are capable of growing and persisting on the surfaces of fresh produce and can inhibit the growth of S. enterica. Significance and Impact of the Study: Our PLAB can be used to reduced the growth of S. enterica on fresh produce and thus reduce the incidence of foodborne disease associated with produce.