Application of bacteriophages against pathogenic Escherichia coli in food

Date

2023-12-11

Author

Dülger, Murat Muhammet

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Escherichia coli (E. coli) is a Gram-negative bacterium that is abundantly found in the intestines of the human body and plays an important role in maintaining the health of the intestinal tract. However, some strains of E. coli are pathogenic and can cause serious intestinal health problems, including death. Foodborne outbreaks associated with pathogenic strains of E. coli are a significant public health concern. In order to eliminate these and other types of pathogens, countless antimicrobial agents are used. However, bacteria have the ability to develop resistance to these agents and when these bacteria multiply, genetic materials containing antimicrobial resistance properties are transferred to daughter cells. Therefore, resistance accumulates over time as a result of using other antimicrobial agents. At this point, bacteriophages can offer a promising approach in inactivating bacteria. In this study, 11 E. coli bacteriophages were isolated from wastewater samples and fecal samples of poultry and cattle, and another was provided by METU Food Safety Laboratory. 12 phages were tested for their host range and titer. Among those, 6 phages with wide host range and high titer were selected for whole genome sequencing. 2 of those phages, coded as MET P1-322 and P1-346, were selected for further analyses since they did not have antimicrobial resistance genes in their genome. One-step growth curve analysis, planktonic killing assay, lyophilization and food experiments were conducted. MET P1-322 and P1-346 were found to have latent periods of approximately 42 and 48 minutes, respectively. Their virulence indices were calculated as 0.67 for P1-322 and 0.85 for P1-346. When these phages were tested on poultry meat, P1-322 was found to reduce the bacterial load by 2-log CFU/mL and P1-346 was found to reduce by 1.5-log CFU/mL. After a month, the titers of the phages that were dried successfully via lyophilization, dropped by 1-log and 4-log PFU/mL, respectively.

Subject Keywords

Escherichia coli, Bacteriophages, Food safety, Foodborne pathogens

URI

https://hdl.handle.net/11511/107739

Collections

Graduate School of Natural and Applied Sciences, Thesis