Publication Date

2022

Document Type

Dissertation

Committee Members

Oleg Paliy, Ph.D. (Advisor); Don Cipollini, Ph.D. (Committee Member); José Ángel Rufián-Henares, Ph.D. (Committee Member); Jeffrey L. Peters, Ph.D. (Committee Member); John V. Paietta, Ph.D. (Committee Member)

Degree Name

Doctor of Philosophy (PhD)

Abstract

Study of human gut microbiota is becoming widely popular in recent years, especially due to numerous beneficial aspects attributed to this diverse and complex microbial communities. Followingly, there is a keen interest in understanding the dynamics and subsequent modulation of human gut microbiota, from a health perspective. Diet is considered significant in shaping gut microbiota community and functions, predominantly due to dietary macro and micronutrient content. Subsequently, a plethora of research is carried out on the effects of dietary nutrients on gut microbiota. Dietary patterns, quality of the diet, differences in food preparation methods, physiological and chemical changes occurred during food preparation, presence of phytochemicals and other bioavailable compounds, as well as food additives varying from dietary supplements to artificial sweeteners, could be categorized as major diet-associated factors. However, when the dietary impact on gut microbiota is discussed, effect of such diet-associated factors is generally overlooked. Hence, in this dissertation, I investigated the effect of different diet-associated factors: diet quality, cooking methods, presence of melanoidins, and consumption of asparagus, which is gaining popularity as a dietary supplement, on human gut microbiome. For this purpose, I profiled gut microbiota from fecal samples to samples generated from different in vitro systems including the human in vitro gut simulator (HGS). HGS is a validated system to study temporal changes of human colonic microbiota, and the use of HGS enables us to distinct the changes in microbial communities with respect to specific regions of the colon. I used novel metagenomic prediction tools to infer overall functional capacity and measured the microbial metabolite production through short chain fatty acids (SCFA) and antioxidants. I used numerous multivariate statistical tools, including both exploratory and discriminatory analyses, to investigate these complex microbiota-related datasets to deduce the influence of such dietary associations on observed changes on gut microbiota profiles and functions. Observations from these multiple studies show that different dietary associations have distinctive impacts on shaping human gut microbiota. I also present the first ever observation of microbial fermentation of asparagus digest and subsequent community and functional differences of human gut microbiota. Overall results of this dissertation provided valuable insights to further our understanding of how dietary associations influence gut microbiota community structure and function. Understanding the effects of dietary associations on gut microbiota, would help the overall modulation of human gut microbiome through diet.

Page Count

121

Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded

2022

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