Date of Graduation

12-2018

Document Type

Thesis

Degree Name

Master of Science in Cell & Molecular Biology (MS)

Degree Level

Graduate

Department

Cell & Molecular Biology

Advisor/Mentor

Sun, Xiaolun

Committee Member

Hargis, Billy M.

Second Committee Member

Kwon, Young Min

Third Committee Member

Huang, Yan

Keywords

Food safety; Poultry science

Abstract

Campylobacter jejuni is a prevalent infectious enteritis mainly foodborne from chickens. Despite of reducing C. jejuni food contamination dramatically decreases campylobacteriosis, few effective approaches are available for the bacterial reduction in chickens. The aim of this study was to use microbial metabolic product deoxycholic acid (DCA) to reduce C. jejuni chicken colonization. Broiler chicks were fed 0 or 1.5 g/kg DCA, lithocholic acid (LCA), or urodeoxycholic acid (UDCA) in diets or orally gavaged with cholic acid (CA, 1.5g/kg body weight). Birds were also transplanted with DCA modulated anaerobes (DCA-Anearo) or aerobes (DCA-Aero). Birds were infected with 109 CFU/bird human clinical isolate C. jejuni 81-176 or chicken isolate C. jejuni AR101 and were weighed or sacrificed to enumerate cecal C. jejuni colonization levels. C. jejuni was culture in broth with various concentrations of DCA, CA, and taurocholic acid (TCA). DCA modulated microbiota were analysis by real time PCR at phylum level. Notably, C. jejuni 81-176 was readily colonized intestinal tract at 105 CFU/g cecal digesta at d16 and reached an almost plateau of 2.8x107 CFU/g cecal digesta at d21. Remarkably, DCA excluded C. jejuni cecal colonization at 100, 99.997, and 100% at 16, 21, and 28 days of age. DCA also improved chicken growth performance of body weight gain compared to infected control birds (1.45 vs. 1.29 kg/bird) at d28. Interestingly, DCA failed to inhibit C. jejuni 81-176 in vitro growth. Neither chicken ages of infection nor CA, LCA or UDCA altered C. jejuni AR101 chicken colonization level, while DCA reduced 91% of the bacterium in chickens at d28. Notably, DCA diet induced a distinct microbiota composition of phyla firmicutes (82.7.1 vs. 98.8%) and bacteroidetes (16.9 vs. 0.8%) compared to infected control birds. Importantly, DCA-Anaero attenuated 93% of C. jejuni colonization at d28 compared to control infected birds (1.79x106 vs. 2.52x107 CFU/bird). In conclusion, DCA shapes microbiota composition against C. jejuni colonization in chickens, suggesting a bidirectional interaction between microbiota and microbial metabolites. Simultaneously reconstituting both microbiota and microbial metabolites may render better therapeutic effect against enteritis or pathogen colonization.

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