# Impact of gut microbial metabolism on host breath volatiles

> **NIH NIH F30** · WASHINGTON UNIVERSITY · 2022 · $32,686

## Abstract

Project Summary/Abstract
The gut microbiome has been implicated in various diseases such as inflammatory bowel disease, asthma, and
neurodegenerative diseases. Despite the progress made in the studies of these diseases, there remains
remarkable heterogeneity in patient presentation and prognosis. The interindividual variability in gut microbiome
composition and metabolic functions may in part explain the interindividual variability in disease. Characterization
of the gut microbiome is typically carried out using metagenomic sequencing or marker gene sequencing of the
V4 16S sequence of bacteria in stool; however, these methods are not always possible in a clinical setting.
Human stool must be acquired, properly stored, and is often not readily available at the site and time of collection
for a clinical study. Metabolomic analysis of stool or urine also provides information about the functions of the
bacteria present in the gut microbiome, however there is yet an even more convenient sample that carries
information relevant to human health. In this project I propose to investigate the breath volatile profile as a
medium for characterizing the gut microbiome. There are over 800 volatile organic compounds (VOC) that have
been detected in human breath, some of them unexplained by host cellular metabolism. I hypothesize that the
gut microbiota contributes otherwise unexplained VOCs to the host breath VOC profile. In Specific Aim 1
I will characterize the breath VOC profile of gnotobiotic mice to test the effect of gut microbiome composition on
the breath VOC profile. In Specific Aim 2 I will show that bacterial metabolism directly produces VOCs that are
absorbed by the host and excreted in breath with a monocolonized gnotobiotic mouse model. Finally, in Specific
Aim 3, I will determine the effect of the microbiome on human breath by comparing the results of metagenomic
sequencing of human stool with human breath VOCs collected as part of a recently completed clinical study.
This investigation will take place at Washington University in St. Louis, a renowned institution for microbiome
research, in the laboratory of Dr. Andrew Kau, an expert in the study of the microbiome and its interactions with
the host. To supplement my training and expertise, I will collaborate with the laboratory of Dr. Audrey Odom-
John, an expert in breath volatile profiling. Further supporting my mentorship team, Dr. Gautam Dantas will
provide excellent advice as a co-sponsor and the chairperson of my thesis committee. This excellent training
environment will ensure the research plan proposed provides rigorous scientific training for me as future
physician-scientist.

## Key facts

- **NIH application ID:** 10505835
- **Project number:** 5F30DK127584-02
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Ariel Jose Hernandez-Leyva
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $32,686
- **Award type:** 5
- **Project period:** 2021-06-01 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10505835

## Citation

> US National Institutes of Health, RePORTER application 10505835, Impact of gut microbial metabolism on host breath volatiles (5F30DK127584-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10505835. Licensed CC0.

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