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P1-135 Investigating the Effect of Salmonella Biocontrol Agent Paenibacillus alvei and Poultry Litter Soil Amendment on the Eastern Shore Tomato Microbiome

Monday, August 4, 2014
Exhibit Hall D (Indiana Convention Center)
Sarah Allard, University of Maryland, College Park, MD
Anna Wallis, University of Maryland, College Park, MD
Elizabeth Prinkey, University of Maryland, College Park, MD
James Pettengill, U.S. Food and Drug Administration, College Park, MD
Jie Zheng, U.S. Food and Drug Administration-CFSAN, College Park, MD
Andrea Ottesen, U.S. Food and Drug Administration, College Park, MD
Christopher Walsh, University of Maryland, College Park, MD
Eric Brown, U.S. Food and Drug Administration-CFSAN, College Park, MD
Peter Evans, U.S. Food and Drug Administration, College Park, MD
Shirley Micallef, University of Maryland, College Park, MD
Introduction: Through laboratory, growth chamber, and field studies, a strain of Paenibacillus alvei, TS-15, has demonstrated potential to decrease the incidence of foodborne pathogen Salmonella enterica in tomato plants. Although TS-15 was isolated from agricultural soil, when applied to the field its concentration will be magnified in the environment.  For responsible management of this biocontrol, it is important to understand how intensifying its presence in tomato fields under various soil management practices could affect resident microbial assemblages in the tomato phyllosphere and rhizosphere. 

Purpose: The purpose of this study was to investigate the influence of biocontrol application with or without chicken litter soil amendment on the microbial ecology and foodborne pathogen risk of an eastern shore tomato field.

Methods: Tomatoes were field-grown with treatments including chicken litter soil amendment and TS-15 application. Microbial communities collected from roots and blossoms were described by 16S sequencing, performed by Illumina MiSeq and analyzed using QIIME. Microbiological methods including direct plating and enrichment were used to screen for Escherichia coli, Salmonella, and Enterococcus spp. on tomato plant organs throughout the season.

Results: Principal component analysis showed that tomato root and blossom bacterial communities differed in phylogenetic composition. Biocontrol treatment had no effect on blossom and root bacterial communities, while chicken litter soil amendment resulted in separate clustering for both roots and blossoms. There were no differences in E. coli, Salmonella, or Enterococcus levels between treatments (P > 0.05).

Significance: The data suggest that the application of TS-15 does not impact root or blossom bacterial communities associated with tomato plants, indicating that its use as a food safety biocontrol will not have negative effects on microbial processes integral to plant health. Chicken litter treatment could have implications for food safety; the microbial makeup of soil amendments may influence microbial diversity and function throughout the plant.

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