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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Research Project #430338

Research Project: Ecology and Detection of Human Pathogens in the Produce Production Continuum

Location: Produce Safety and Microbiology Research

Project Number: 2030-42000-050-00-D
Project Type: In-House Appropriated

Start Date: Dec 28, 2015
End Date: Dec 27, 2020

Objective:
Objective 1: Elucidate biological factors and molecular mechanisms that enhance or reduce fitness characteristics related to survival and growth of enteric pathogens in the produce production continuum. Sub-objective 1A-1I (Refer to uploaded Project Plan) Objective 2: Identify environmental factors that affect the persistence and transmission of enteric pathogens in the produce production environment for risk assessment. Sub-objective 2A-2H (Refer to uploaded Project Plan) Objective 3: Develop methods for the detection and subtyping of enteric bacterial and viral pathogens from produce production environments; to aid epidemiological investigations and to distinguish pathogenic from non-pathogenic strains. Sub-objective 3A-3E (Refer to uploaded Project Plan) Objective 4: Study the ecology of Shiga toxin-producing E. coli (STEC) bacteriophages and its association with bacterial hosts. Objective 5: Development of immuno-, bacteriophage-, and mass spectrometry-based methods for rapid detection of foodborne pathogens.

Approach:
Plant-microbe model systems in combination with population studies, ecology, molecular methods, genomics, and microbiology will be used to investigate the interaction of human bacterial and viral pathogens with plants and plant-associated bacteria, as well as to develop improved methods for detection and subtyping of human on produce. Pathogenic E. coli is a foodborne pathogen that has been linked to numerous outbreaks of foodborne illnesses, and the illnesses are primarily attributed to the ingestion of Shiga toxin-producing E. coli (STEC). Previous research has indicated the virulence markers such as stx genes, of STEC strains are conferred to stx-encoding bacteriophages and can be transduced into the susceptible bacterial hosts. In order to understand the interplay between STEC-specific phages and their bacterial hosts in the environment to enhance the safety of food products and the prevention of new emerging foodborne pathogens, the initial focuses of the phage research are to isolate, collect and characterize STEC phages and to understand the relationship between phages and their hosts in the environment. Efficient methods for isolation of STEC bacteriophages will be utilized. Characterization of STEC bacteriophages will be established using genomic sequencing and proteomic analyses. The association of fecal contamination with the population of STEC bacteriophages in the environment will be determined. Environmental factors that influence the geographical distribution of STEC bacteriophages will be identified. This will establish a foundation to study biological interactions between phages and their hosts and the association of phages with bacterial evolution as well as to utilize collected phages to develop biosensors and pre-harvest biological controls for STEC to improve the microbiological food safety of the food supplies.