Theses and Dissertations

Advisor

Shecoya, White

Committee Member

Komakech, Joel

Committee Member

Mlsna, Todd

Committee Member

Cheng, Wen-Hsing

Date of Degree

8-7-2025

Original embargo terms

Immediate Worldwide Access

Document Type

Dissertation - Open Access

Major

Food Science, Nutrition, and Health Promotion

Degree Name

Doctor of Philosophy (Ph.D.)

College

College of Agriculture and Life Sciences

Department

Department of Biochemistry, Nutrition and Health Promotion

Abstract

Selenoprotein H (SELENOH) is an oxidoreductase located in the nucleolus, and its biochemical levels decrease with selenium (Se) deficiency, as reported in mammalian research. This current investigation aimed to understand the impact of nutritional Se deficiency on gut microbial composition and metabolomic profiles. The Firmicutes/Bacteroidota (F/B) ratio, linked to various health conditions, was balanced for wildtype (WT) mice (1.06). In contrast, selenoh knockout (KO) mice associated with dietary Se deprivation had a significantly (p < 0.002) lower ratio (0.56), suggesting dysbiosis. It is believed that SELENOH levels decreased due to the Se deficient diet, and the selenoh KO mice exhibited alterations in microbial community composition and metabolite profiles, as supported by correlative analyses. With respect to the bacterial communities, significant differences between diets occurred for three taxa, including Akkemansia mucinphila, Bacteroides caecimuris, and Parabacteroides goldsteinii. Candida tropicalis, Malassezia restricta, and Cyberlindnera jadinii were three abundant fungal yeasts. Only Cyberlindnera jadinii exhibited significantly greater relative abundance between genotypes and was more abundant in the selenoh KO versus WT mice. Correlation analyses between bacterial and fungal taxa revealed both positive and negative relationships, but no specific trends were observed. The liver and serum metabolomic data contained similar amino acids, lipids, proteins, and carbohydrates. Using NMR spectroscopy, 112 liver metabolites were detected, while GC-TOF-MS analysis of the serum revealed the presence of 172, comprising both polar and nonpolar compounds. The metabolite levels varied significantly when analyzed using multivariate models such as PCA and PLS-DA (VIP scores), particularly for glucose, taurine, lactate, and UDP-glucose, which are associated with energy production and cellular health. Overall, the Se deficient diet had the most significant impact on the microbial community structure and the concentration of key metabolites within liver tissues and serum. Correlation analyses conducted across studies revealed significant linear relationships between metabolites and the microbiome. However, these differences were associated with bacterial and fungal taxa containing low relative abundances. Based on these findings, further investigation into the impact of SELENOH homeostasis on microbial and metabolite profiles should be conducted using selenoh KO mice under various nutritional Se dietary levels.

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