Date of Graduation


Document Type


Degree Name

Doctor of Philosophy in Cell & Molecular Biology (PhD)

Degree Level



Biological Sciences


Xiaolun Sun

Committee Member

Adnan Alrubaye

Second Committee Member

Chenguang Fan

Third Committee Member

Young Kwon

Fourth Committee Member

Joshua Lyte


C.jejuni, chicken, colonization, meat, microbiota, poultry productivity, Specific pathogen free


The successful poultry production at modern era comes from the vertical integratedindustrialization, which has fundamentally changed how animals have been living for millions of years. Antimicrobial growth promoters have been used to sustain the efficient industrialized animal production, driving antimicrobial overuse and resistance. Because of the increasing pressure from consumer’s concerns and government regulations, it is urgent to develop antimicrobial free alternatives as growth promoters in poultry production, but few effective antimicrobial alternatives are currently available. Campylobacter jejuni is one of the worldwide prevalent foodborne bacterial pathogens mainly transmitted from poultry. However, few mechanisms are available on why C. jejuni colonizes chickens. In the first chapter, I have presented an overview of current knowledge on microbiota, chicken growth and C. jejuni infection.

In the second chapter, we aimed to investigate the mechanism of transplanting microbiota on C. jejuni chicken colonization. Mouse specific pathogen free (SPF) microbiota was cultured on Brain Heart Infusion agar (BHI) and collected as SPF-Aerobe and SPF-Anaerobe. Birds raised on floor pens were colonized with 108 CFU/bird SPF-Aerobe and SPF-Anaerobe at d 0 and infected with 109 CFU/bird C. jejuni chicken isolate AR101 at d 12. Birds were sacrificed at d 21 and 28 to enumerate C. jejuni cecal colonization on selective Campylobacter plates. The results show both SPF- Aerobe and SPF-Anaerobe microbiota reduced C. jejuni chicken colonization compare to infected birds at d 21 and 28, Also, we found that SPF-mouse microbiota was able to colonize in chicken gut by modulating chicken microbiota at phylum level. Furthermore, SPF-mouse microbiota prevented C. jejuni growth in vitro.

In the third chapter, we investigated investigate the effect of transplanting microbiota on the bird growth performance. Mouse SPF stool was cultured on Brain Heart Infusion (BHI) agar under anaerobic or aerobic condition and collected as SPF-Aerobe and SPF-Anaerobe microbiota. Day-old birds were tagged, weighed, and randomly assigned to 8 pens with 15 birds/pen. The birds were orally gavaged with PBS (3 pens), 108 CFU/bird SPF-Aerobe (2 pens) or SPF-Anaerobe (3 pens). The feed intake and individual bird weight were measured at d 0, 14, 21 and 28. The broiler chickens were euthanized at d 14, 21 and 28. Intestinal digesta was collected to measure nutrient and bacteria levels. Notably, SPF-Aerobe and SPF-Anaerobe significantly increased body weight gain by 18% and 12% during d 0 to d 14, respectively, compared to the negative control. No significant difference of feed intake was observed among the groups. SPF-Aerobe significantly reduced periodic feed conversion ratio compared to the negative control by 20% during d 21 to 28. Both SPF-Aerobe and SPF-Anaerobe microbiota reduced accumulative feed conversion ratio compared to negative control by 18% and 14% respectively, during d 0-28. SPF microbiota increased the levels of macro-nutrients of gross energy, protein and fat in the digesta of the small intestine compared to the negative control. SPF-Anaerobe transplantation increased phylum Bacteroidetes but reduced Firmicutes in the digesta of small intestine and ceca compared to the negative control. In conclusion, microbiota was able to reduce C. jejuni chicken colonization and to improve feed efficiency and early bird body weight gain. The results suggest that microbiota reconstitution in chickens could be used an effective antibiotic alternative to reduce foodborne pathogen C. jejuni and to improve poultry productivity.