Bacillus amyloliquefaciens ALB65 Inhibits the Growth of Listeria monocytogenes on Cantaloupe Melons

Thao D Tran; Celia Del Cid; Robert Hnasko; Lisa Gorski; Jeffery A McGarvey

doi:10.1128/AEM.01926-20

Bacillus amyloliquefaciens ALB65 Inhibits the Growth of Listeria monocytogenes on Cantaloupe Melons

Appl Environ Microbiol. 2020 Dec 17;87(1):e01926-20. doi: 10.1128/AEM.01926-20. Print 2020 Dec 17.

Authors

Thao D Tran¹, Celia Del Cid², Robert Hnasko³, Lisa Gorski³, Jeffery A McGarvey⁴

Affiliations

¹ University of California, Department of Fish, Wildlife, and Conservation Biology, Davis, California, USA.
² USDA, ARS, Foodborne Toxin Detection and Prevention Research Unit, Albany, California, USA.
³ USDA, ARS, Produce Safety and Microbiology Research Unit, Albany, California, USA.
⁴ USDA, ARS, Foodborne Toxin Detection and Prevention Research Unit, Albany, California, USA jeffery.mcgarvey@usda.gov.

Abstract

Listeria monocytogenes is a foodborne pathogen that causes high rates of hospitalization and mortality in people infected. Contamination of fresh, ready to eat produce by this pathogen is especially troubling because of the ability of this bacterium to grow on produce under refrigeration temperatures. In this study, we created a library of over 8,000 plant phyllosphere-associated bacteria and screened them for the ability to inhibit the growth of L. monocytogenes in an in vitro fluorescence-based assay. One isolate, later identified as Bacillus amyloliquefaciens ALB65, was able to inhibit the fluorescence of L. monocytogenes by >30-fold in vitro. B. amyloliquefaciens ALB65 was also able to grow, persist, and reduce the growth of L. monocytogenes by >1.5 log CFU on cantaloupe melon rinds inoculated with 5 × 10³ CFU at 30°C and was able to completely inhibit its growth at temperatures below 8°C. DNA sequence analysis of the B. amyloliquefaciens ALB65 genome revealed six gene clusters that are predicted to encode genes for antibiotic production; however, no plant or human virulence factors were identified. These data suggest that B. amyloliquefaciens ALB65 is an effective and safe biological control agent for the reduction of L. monocytogenes growth on intact cantaloupe melons and possibly other types of produce.IMPORTANCEListeria monocytogenes is estimated by the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration to cause disease in approximately 1,600 to 2,500 people in the United States every year. The largest known outbreak of listeriosis in the United States was associated with intact cantaloupe melons in 2011, resulting in 147 hospitalizations and 33 deaths. In this study, we demonstrated that Bacillus amyloliquefaciens ALB65 is an effective biological control agent for the reduction of L. monocytogenes growth on intact cantaloupe melons under both pre- and postharvest conditions. Furthermore, we demonstrated that B. amyloliquefaciens ALB65 can completely inhibit the growth of L. monocytogenes during cold storage (<8°C).

Keywords: Bacillus amyloliquefaciens; Listeria monocytogenes; biocontrol; cantaloupe; secondary metabolites.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Bacillus amyloliquefaciens / physiology*
Biological Control Agents / pharmacology*
Cold Temperature
Cucumis melo / microbiology*
Food Handling
Food Microbiology*
Listeria monocytogenes / physiology*

Substances

Biological Control Agents