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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Research Project #441636

Research Project: Factors Affect the Transfer of Bacterial Pathogens to Leafy Greens from Soils

Location: Environmental Microbial & Food Safety Laboratory

Project Number: 8042-42610-001-008-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: May 1, 2022
End Date: Jul 31, 2024

The objective of this study is to determine if the practice of 'side-dressing' (adding organic fertilizers to soils during a cropping cycle) can affect the survival of foodborne bacterial pathogens like E. coli O157:H7 in soils, and also affect the transfer of these pathogens from soils to Romaine lettuce plants.

Methods: Non-pathogenic and pathogenic E. coli used in field trials and cultured in simulated runoff will be introduced to soils used to grow leafy green commodities ina BSL-2 growth chamber immediately prior to planting of Romaine lettuce or spinach seedlings (depending on region). Heat treated poultry pellets (HTPP) with a 3-2-3, N-P-K will be added at agronomically appropriate rates through the growing season, and control (not side-dressed) plots will be monitored. Soils (but not plants) will be inoculated with pathogens (Escherichia coli O157:H7, Salmonella) in a BSL-2 controlled access plant growth chamber. Longitudinal microbial sampling for inoculated and indigenous E. coli will be adjusted so that soil samples are analyzed immediately before and after side-dressing occurs. Foliar samples will also be analyzed for non-pathogenic E. coli. Microbial methods described in sub-objective 2.1 will be used. Expected Outcomes: Collected data will establish if plots receiving treated BSAAO (HTTP) during the leafy green growing season increases likelihood of survival or contamination of leafy greens with enteric pathogens. Means by which results will be analyzed, assessed, or interpreted: Previously used statistical models and methods describing bacterial population declines in HTPP-amended soils will be utilized.