Date of Graduation

8-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Poultry Science (PhD)

Degree Level

Graduate

Department

Poultry Science

Advisor/Mentor

Dan J. Donoghue

Committee Member

Casey M. Owens

Second Committee Member

Annie M. Donoghue

Third Committee Member

Charles F. Rosenkrans, Jr.

Keywords

Antibiofilm effect, Antimicrobial coating, Antimicrobial wash, Campylobacter jejuni, Eugenol, Gene expression

Abstract

Campylobacter jejuni infection in humans is strongly associated with the handling and consumption of contaminated poultry products. Interventions reducing C. jejuni contamination in poultry would reduce the risk of subsequent human infections. In the first study, the efficacy of a Generally Recognized as Safe (GRAS) compound, eugenol (EG; derived from cloves), as an antimicrobial dip treatment to reduce C. jejuni in postharvest poultry was evaluated. The antimicrobial efficacy of EG was studied in suspension, emulsion and nanoemulsion delivery systems. EG suspension reduced C. jejuni counts with the greatest reduction of >2.0 Log CFU/sample for the 2% dose of EG (P<0.05). Eugenol emulsions or nanoemulsions did not provide any additional Campylobacter reduction when compared with suspension alone. In the second study, the efficacy of pectin or chitosan coatings fortified with eugenol to reduce C. jejuni on chicken wingettes was investigated. Inoculated wingettes were randomly assigned to controls, eugenol (0.5, 1 or 2%), pectin (3%), chitosan (2%) or their combinations. Following 1 min of coating, wingettes were air dried (1 h) and sampled on d 0, 1, 3, 5, and 7. The incorporation of 0.5, 1 or 2% eugenol in the pectin improved coating efficacy against C. jejuni whereas the efficacy of chitosan coating was improved by 2% eugenol treatment (P<0.05). Exposure of C. jejuni to eugenol, chitosan or combination significantly modulated select genes encoding for motility, quorum sensing and stress response. In the third study, the efficacy of eugenol, trans-cinnamaldehyde and carvacrol in inhibiting C. jejuni biofilm formation and inactivating mature biofilm was evaluated. For the inhibition study, C. jejuni was grown either in the presence or absence of sub-inhibitory concentrations of phytochemicals and biofilm formation was quantified at 24 h intervals by enumeration. For the inactivation study, mature C. jejuni biofilms were exposed to the phytochemicals (0, 0.25, 0.5, or 1%) for 1, 5, or 10 min, and surviving C. jejuni in the biofilms were enumerated. All phytochemicals reduced C. jejuni biofilm formation as well as inactivated mature biofilm at both temperatures (P<0.05). Moreover, scanning electron microscopy revealed disruption of biofilm architecture and loss of extracellular polymeric substances after treatment.

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