# Mechanism of colonization resistance

> **NIH AI R01** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2026 · $652,995

## Abstract

ABSTRACT
Our gut microbiota protects us from infection through a phenomenon called colonization resistance. Established
microbes confer colonization resistance by blocking harmful invaders through consumption of critical nutrients
and altering the gut environment. Among these protective microbes, certain “keystone species” play an outsized
role, yet what makes them so effective remains incompletely understood. Our work focuses on E. coli Nissle
1917, a probiotic strain that shields against Salmonella infection. We hypothesize that its protective power stems
from its ability to migrate into specific intestinal niches where it competes directly with Salmonella for simple
sugars, overcoming inhibitory metabolites and preempting the pathogen’s growth. In Specific Aim 1 we will
determine the mechanism through which consumption of simple sugars by E. coli limits Salmonella growth. In
Specific Aim 2 we will determine the mechanism by which chemotaxis contributes to colonization resistance.
Using a combination of animal modeling and an innovative in vitro gut habitat model, completion of these aims
will define the metabolic and behavioral traits that make E. coli a keystone defender. Understanding these
principles will not only reveal how probiotics work but also open new avenues for preventing infections by
reshaping the gut ecosystem itself.

## Key facts

- **NIH application ID:** 11385998
- **Project number:** 2R01AI112949-10
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Andreas J Baumler
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** AI
- **Fiscal year:** 2026
- **Award amount:** $652,995
- **Award type:** 2
- **Project period:** 2014-08-20T00:00:00 → 2031-04-30T00:00:00

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11385998

## Citation

> US National Institutes of Health, RePORTER application 11385998, Mechanism of colonization resistance (2R01AI112949-10). Retrieved via AI Analytics 2026-07-13 from https://api.ai-analytics.org/grant/nih/11385998. Licensed CC0.

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