Project Number: 1265-32630-002-06
Project Type: Specific Cooperative Agreement

Start Date: Sep 01, 2002
End Date: Aug 31, 2005

Objective:
To determine 1) ecological factors influencing attraction of two free-living nematodes, Caenorhabditis elegans and Diploscapter sp., to Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes; 2) effects of manure, compost, and manure-amended soil inoculated with foodborne pathogens on growth and reproduction of free-living nematodes; 3) dispersal and survival of pathogens after death of nematodes; and 4) effectiveness of produce sanitizers in killing foodborne pathogens internalized by free-living nematodes.

Approach:
Cells of pathogenic bacteria tagged with GFP (several strains each of Salmonella, E. coli 0157:H7, and L. monocytogenes) will be used in studies to monitor their dispersal by C. elegans. Studies will be extended to include another free-living soil nematode, Diploscapter sp. Nematode movement toward colonies, manure/soil, or pieces of fresh produce on agar will be video captured and images analysed at predetermined times over a 16-to 20-min period, followed by a 24 h exam to check their dispersal; and Attracting Activity Index will be calculated for each bacterial strain. A second assay will be used to determine the survival of any ingested bacteria after nematode surfaces are washed and worms are killed.