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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Research Project #441458

Research Project: Assessing Romaine Lettuce "Forward Processing" for Potential Impacts on EHEC Growth, Antimicrobial Susceptibility, and Infectivity

Location: Environmental Microbial & Food Safety Laboratory

Project Number: 8042-32420-009-029-A
Project Type: Cooperative Agreement

Start Date: Jan 1, 2022
End Date: Nov 30, 2023

Several large scale outbreaks of foodborne infections in the past few years were associated enterohemorrhagic E. coli (EHEC) contamination of romaine lettuce. In this agreement, ARS scientists will collaborate with researchers at University of Maryland in further understanding the causes of these outbreaks, with the following specific objectives: 1) Comprehensive assessment of forward processing practice under routine operationconditions for product integrity and microbiological quality. 2) Assessment of microbiome dynamics on Romaine lettuce from harvest to retail for products being forward and source processed. 3) Comparative assessment of E. coli O157:H7 outbreak strains and laboratory strains, and the impacts of different practices on EHEC outbreak strains, on cell physiology that may affect their growth potential, susceptibility to antimicrobial treatment, or virulence.

Forward processing is a common practice by the leafy green industry to transport raw commodity from the growing regions in California and Arizona to Eastern US population centers for fresh-cut processing and distribution. There has been concerns from the industry that such practices might enhance the risks foodborne pathogen survival, especially for enterohemorrhagic Escherich coli (EHEC), which is associated with repeated foodborne outbreaks in the past years. The research team will closely collaborate with the leafy green industry to systematically characterize the risks associated with forward processing by analyzing microbiome dynamics on romaine lettuce subjected to forward processing and physical stresses on romaine lettuce during the transportation. The forward processing will be simulated in the laboratory with the outbreak strains of EHEC, and the effect of the simulation on EHEC physiology, gene expression, survivability, and infectivity will be comprehensively assessed. The results will be feedback to the industry partners for assessing risks associated with forward processing, and for improving the process.