# Metabolic Interactions between Salmonella and E. coli Nissle 1917

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2023 · $200,000

## Abstract

PROJECT SUMMARY
Infection with Salmonella enterica serovar Typhimurium (S. Tm) is a common cause of
inflammatory diarrhea. As part of the infection process, S. Tm colonizes the intestinal tract
and competes with the microbiota for nutrients. Gut-associated microbial communities
antagonize invasion of the ecosystem by enteric pathogens (colonization resistance). The
molecular mechanisms of how colonization resistance is achieved remain incompletely
understood. Our preliminary data suggest that E. coli Nissle 1917, an E. coli strain with
presumed probiotic properties, prevents S. Tm gut colonization and intestinal inflammation
by competing efficiently for the respiratory electron acceptor nitrate, a limiting nutrient. We
hypothesize that EcN uses one or more siderophore systems to acquire sufficient iron for
the iron-sulfur cluster-containing nitrate reductases and to produce high levels of nitrate
reductase activity. We will test key aspects of our hypothesis in mouse models of infection
and in vitro using a strategic combination of bacterial and host genetics. We will pursue
the following specific aims: 1. Investigate how EcN and S. Tm compete for nitrate in the
mouse intestine, and 2. Determine whether siderophore-mediated uptake of iron is
required for nitrate reductase activity. This work will advance our understanding of how
intestinal pathogens, such as S. Tm, and commensal microbes compete for limiting
resources in the intestinal tract. These studies are also expected to reveal a molecular
property of a probiotic strain, which may help devise novel intervention strategies for
Salmonella gastroenteritis.

## Key facts

- **NIH application ID:** 10663378
- **Project number:** 5R21AI171537-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Sebastian E Winter
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $200,000
- **Award type:** 5
- **Project period:** 2022-07-11 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10663378

## Citation

> US National Institutes of Health, RePORTER application 10663378, Metabolic Interactions between Salmonella and E. coli Nissle 1917 (5R21AI171537-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10663378. Licensed CC0.

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