Graduate Studies


First Advisor

Jacques Izard

Date of this Version


Document Type



A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Food Science and Technology, Under the Supervision of Professor Jacques Izard. Lincoln, Nebraska: May 2023

Copyright © 2023 Linda H Xu


Ostomy is a life-saving surgery for severe gastrointestinal and medical conditions, such as Crohn’s disease, colitis, and colorectal cancer. However, many ostomates experience physical and emotional distress which significantly reduces their quality of life. In this study, we analyzed the concentrations of 8 short chain fatty acids (SCFAs) and lactic acid of ileostomy, colostomy, and control groups using LC-MS/MS; we also correlated this data with the abundance of potential bacteria producers or utilizers detected through Illumina Miseq sequencing of DNA extracted from these samples. Results of this study revealed the drastic reduced concentrations of eight tested SCFAs and elevated lactic acid concentrations in ileostomates, but not in colostomates, compared to the control. In addition, we observed significant positive correlations between metabolite producers and corresponding metabolites for lactic acid, propionic acid, butyric acid, isobutyric acid, and isovaleric acid, and significant negative correlations between metabolite utilizers and corresponding metabolites for lactic acid and acetic acids; a significant negative correlation between levels of acetate producers and fecal acetic acid were found in the whole population. Analyses of diet and symptom was also performed across the groups. This study provides valuable data for identifying biomarkers for future treatment and improving management of daily life for ostomates.

Advisor: Jacques Izard