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Acid resistance in Escherichia coli
Hope T Richard1, John W Foster
1Department of Microbiology and Immunology, College of Medicine, University of South Alabama Mobile, Alabama 36688, USA.
Advances in Applied Microbiology
|September 11, 2003
Summary
Escherichia coli utilizes three distinct acid resistance systems (AR1, AR2, AR3) to survive stomach and intestinal acid stress. These systems are crucial for E. coli
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Enteric pathogens face environmental challenges like acid stress in the host's gastrointestinal tract.
- Escherichia coli (E. coli) employs multiple strategies to survive these harsh conditions.
- Understanding these survival mechanisms is key to controlling infections.
Purpose of the Study:
- To elucidate the inducible acid resistance systems in E. coli.
- To differentiate the protective levels, requirements, and induction conditions of these systems.
- To assess the contribution of these systems to E. coli pathogenesis.
Main Methods:
- Analysis of three known inducible acid resistance systems in E. coli: AR1, AR2, and AR3.
- Investigation of system-specific requirements (e.g., RpoS, glutamate, arginine).
- Evaluation of protection levels at varying pH and induction conditions.
Main Results:
- Acid Resistance System 1 (AR1) is RpoS-dependent, induced by acid in stationary phase, offering minimal pH 2.5 protection.
- Acid Resistance System 2 (AR2) is glutamate-dependent, providing the highest protection.
- Acid Resistance System 3 (AR3) is arginine-dependent, induced anaerobically, offering moderate protection.
Conclusions:
- E. coli possesses multiple, distinct acid resistance systems (AR1, AR2, AR3) that operate under different conditions.
- These systems, along with log-phase tolerance, enable survival across a pH range of 2-4.5.
- These acid resistance mechanisms significantly contribute to E. coli's low infectious dose and overall pathogenesis.