In situ evaluation of Paenibacillus alvei in reducing carriage of Salmonella enterica serovar Newport on whole tomato plants

Appl Environ Microbiol. 2014 Jul;80(13):3842-9. doi: 10.1128/AEM.00835-14. Epub 2014 Apr 18.

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.

MeSH terms

  • Antibiosis*
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Food Microbiology
  • Fruit / microbiology
  • Lycopersicon esculentum / microbiology*
  • Microbial Viability
  • Paenibacillus / classification
  • Paenibacillus / genetics
  • Paenibacillus / isolation & purification
  • Paenibacillus / physiology*
  • Pest Control, Biological*
  • Plant Leaves / microbiology
  • RNA, Ribosomal, 16S / genetics
  • Salmonella enterica / growth & development*
  • Sequence Analysis, DNA
  • Virginia

Substances

  • DNA, Bacterial
  • DNA, Ribosomal
  • RNA, Ribosomal, 16S