Date of Graduation

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Animal Science (PhD)

Degree Level

Graduate

Department

Animal Science

Advisor

Charles V. Maxwell

Committee Member

Jiangchao Zhao

Second Committee Member

Fred W. Pohlman

Third Committee Member

Charles Rosenkrans

Fourth Committee Member

Young Min Kwon

Keywords

gut microbiome, stage, culturomics, probiotics

Abstract

The gastrointestinal tract is a critical place where the immune system concentrates many of its protective functions. It exerts both physical and biochemical defenses against invading foodborne pathogens and other hazards. In pigs, the gut microbiota community assembled postnatal plays a very important role in the development of multiple physiologic aspects, such as development of the gastrointestinal tract, nutrient exchange, immune defense against foreign pathogens and growth performance. Microbiome-host communication changes with age. Despite recent advances in understanding the swine gut microbiome at different growth stages, a comprehensive longitudinal study of the lifelong dynamics of the swine gut microbiome is lacking. Besides, in the current market swine-specific probiotic options are very limited due to the shortage of swine cultivable strains. This is also due to the missing knowledge of practical cultureomic methods in swine research. Large scale probiotic screening can be performed using cell models to reduce cost and increase consistency. Establishing a stable, rapid and dependable model that can facilitate probiotic screening and practical investigations.

In this dissertation, we characterized the longitudinal swine gut microbiome from a total of 18 pigs and determined that gut microbiome structures change with age (Chapter III). A validation trial also confirmed the stage-related microbiome composition and disclosed the difficulty of colonizing the gut of young piglets with an adult pig microbiome. We examined how the gut microbiome amassed and changed with age, how growth stage and diet composition affected the microbiome community, and how this ultimately affects animal health and growth performance. Next, through swine gut microbiome cultureomic techniques (Chapter IV), we established a basic understanding of the number of culturable swine gut bacteria there are through the use of 53 culturing methods applied to fecal samples from each growth stage. Also, we investigated which of these methods is most efficient for the cultivation of certain bacterial species of interest. Finally, an in vitro model was established using IPEC-J2 cells (Chapter V) to screen for useful probiotics and to study their beneficial biological functions. Overall, this dissertation provides valuable insights into swine microbiome research that can lead to meaningful industrial applications.

Available for download on Thursday, July 29, 2021

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