Discipline: Biological Sciences
Subcategory: Plant Research
Room: Exhibit Hall
Carmen Smith - California Polytechnic State University - San Luis Obispo
Co-Author(s): Erin Jennings, University of Delaware, Location: Newark, Delaware
This study attempts to gain an understanding of the persistence and plant transfer of Escherichia coli TVS355 (E. coli TVS355) and Escherichia coli O157H12 (E. coli O157H12) in poultry litter. Poultry litter is a common soil amendment that is used as a fertilizer to grow fruits and vegetables. Similar studies have researched the persistence of Salmonella in poultry litter soil amendments, while also considering irrigation. This study also examines the effect of irrigation on bacterial growth in poultry litter, but with E. coli TVS355 and E. coli O157H12. Both E. coli TVS355 and E. coli O157H12 are non-pathogenic strains of E. coli that can provide insight into how a pathogenic strain of E. coli may act on a poultry litter soil amendment. Examining the persistence of E. coli strains in poultry litter is imperative to food safety as poultry litter is a widely used soil amendment. Potted cilantro plants were inoculated with E. coli TVS355 and E. coli O157H12 in a 15-day trial. The control samples were not inoculated. Half of the inoculated samples were irrigated daily, while the other half of inoculated samples and control samples were not irrigated during the trial. Samples were diluted and plated on MacConkey Agar every five days and counted after 24 hours in the incubator at 37 degrees Celsius. The E. coli TVS355 strain showed a strong persistence in the poultry litter soil amendment as the plate counts were consistently high. The E. coli O157H12 strain was not as persistent as the growth declined throughout the trial. Results for plant transfer of both strains were inconclusive because the roots of the separated cilantro plants often contained soil. Future studies should consider using an alternative method to separate the plants from the soil. The effect of irrigation on the E. coli TVS355 strains remains unclear. The highest plate count for E. coli TVS355 was in an irrigated soil sample, but on other days of the trial non-irrigated samples would occasionally have higher plate counts than the irrigated samples. Irrigated soil samples for E. coli O157H12 had less growth than the non-irrigated samples. Irrigation seemed to discourage growth in the E. coli O157H12 soil samples. The strong persistence of the E. coli TVS355 strain suggests that poultry litter amended farms should be monitored closely, especially for robust strains of bacteria. The decline in growth of E. coli O157H12 suggests that this strain is not a concern in poultry litter amended farms. Further research is needed to confirm these conclusions. A larger sample size, more diverse set of plants, longer trial, and revised sampling technique for the separated plants, may confirm the results of this study.
Funder Acknowledgement(s): University of Delaware College of Agriculture and Natural Resources
Faculty Advisor: Kalmia Kniel, email@example.com
Role: I conducted the sampling and inoculation procedures, for the Escherichia coli TVS355 (E. coli TVS355) strain. These procedures included inoculating cilantro plants with E. coli TVS355, performing dilutions, plating diluted soil and cilantro plant samples on MacConkey Agar, and incubating samples. I also analyzed the results for this strain.