Semester of Graduation

Fall 2017

Degree

Master of Science (MS)

Department

Nutrition and Food Sciences

Document Type

Thesis

Abstract

The compositions of bacterial communities inhabiting the human gut are associated with regulating energy balance, immune response, and neurological functions. Many of these benefits are attributed to byproducts of bacteria that feed on fermentable fibers. Research has shown that obese or lean host can transfer their phenotype to germ-free recipients, via microbiota transplant, without alteration in recipient diet. However, transfer may be attenuated by established microbial communities in conventionally-raised rodents or other species. A knockdown of recipient communities may be required before a transplant for microbiota of donors to populate gut of recipient. This study examined whether obese Zucker Diabetic Fatty (ZDF) rats fed either a high fat (HF) or alow fat high resistant starch (LFRS) diet could transfer microbiota and phenotype to lean ZDF recipient rats after antibiotics (AB, vancomycin and meropenem, 50 mg/kg/bw/day in drinking water for 3 days). Obese ZDF donor groups (n=3) fed above diets were euthanized after six weeks. Cecal contents collected were transplanted separately into two (n=6) groups of LZDF rats subsequent to AB treatment. Some cecal contents were used for culture. LZDF groups were fed chow and euthanized after eight weeks. Emboweled weight, cecum weight, cecal pH and short-chain fatty acids were analyzed. There were no significant (p<0.05) phenotypic differences in recipient groups after 2 rats per group were removed due to skin lesions. However, HF recipients had numerically higher (p=0.1175) insulin resistance (2.390 ± 0.232) than LFRS (1.691 ± 0.232). 16S rRNA sequencing and bioinformatics determined bacterial composition. Phyla Bacteroidetes and Firmicutes and Lactobacillus (genus) decreased after AB. Ruminococcus bromii in RS Donor and phylum Proteobacteria and family Mogibacteriaceae in HF Donor were significantly enriched. LFRS and HF recipient rats, after transplants, displayed differences in Ruminococcus bromii and Mogibacteriaceae indicating a limited effect of transplant. A larger sample size (power for insulin sensitivity 60%) is necessary to measure possible differences in phenotype, and protection methods including encapsulation of transplant bacteria may be needed for viability of all transplanted bacteria. Anaerobic transplant may be required, however, anaerobes and aerobes were cultured from donor cecal contents so some anaerobes may have survived collection.

Date

11-11-2017

Committee Chair

Keenan, Michael

DOI

10.31390/gradschool_theses.4342

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