In Situ Evaluation of Paenibacillus alvei in Reducing Carriage of Salmonella enterica Serovar Newport on Whole Tomato Plants

• DOI: 10.1128/aem.00835-14
• Publication Date: 2014-04-19T02:39:33Z
• Authors: Sarah Allard; Alexander Enurah; Errol Strain; Patricia Millner; Steven L. Rideout; Eric W. Brown; Jie Zheng
• Keywords: DNA, Bacterial; 0301 basic medicine; 2. Zero hunger; Microbial Viability; Virginia; Salmonella enterica; Sequence Analysis, DNA; DNA, Ribosomal; Plant Leaves; 03 medical and health sciences; Solanum lycopersicum; Fruit; RNA, Ribosomal, 16S; Antibiosis; Food Microbiology; Pest Control, Biological; Paenibacillus

ABSTRACT

Recently, tomatoes have been implicated as a primary vehicle in food-borne outbreaks of Salmonella enterica serovar Newport and other Salmonella serovars. Long-term intervention measures to reduce Salmonella prevalence on tomatoes remain elusive for growing and postharvest environments. A naturally occurring bacterium identified by 16S rRNA gene sequencing as Paenibacillus alvei was isolated epiphytically from plants native to the Virginia Eastern Shore tomato-growing region. After initial antimicrobial activity screening against Salmonella and 10 other bacterial pathogens associated with the human food supply, strain TS-15 was further used to challenge an attenuated strain of S . Newport on inoculated fruits, leaves, and blossoms of tomato plants in an insect-screened high tunnel with a split-plot design. Survival of Salmonella after inoculation was measured for groups with and those without the antagonist at days 0, 1, 2, and 3 and either day 5 for blossoms or day 6 for fruits and leaves. Strain TS-15 exhibited broad-range antimicrobial activity against both major food-borne pathogens and major bacterial phytopathogens of tomato. After P. alvei strain TS-15 was applied onto the fruits, leaves, and blossoms of tomato plants, the concentration of S . Newport declined significantly ( P ≤ 0.05) compared with controls. Astonishingly, >90% of the plants had no detectable levels of Salmonella by day 5 for blossoms. The naturally occurring antagonist strain TS-15 is highly effective in reducing the carriage of Salmonella Newport on whole tomato plants. The application of P. alvei strain TS-15 is a promising approach for reducing the risk of Salmonella contamination during tomato production.