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Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
How does Listeria monocytogenes combat acid conditions?
James L Smith1, Yanhong Liu, George C Paoli
1Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8598, USA. james.smith@ars.usda.gov
Canadian Journal of Microbiology
|April 2, 2013
Summary
Listeria monocytogenes survives acidic conditions using an adaptive acid tolerance response (ATR). The glutamate decarboxylase system is crucial for protecting this foodborne pathogen in acidic foods and the stomach.
Area of Science:
- Microbiology
- Food Safety
- Bacterial Pathogenesis
Background:
- Listeria monocytogenes is a significant foodborne pathogen.
- Acidic environments, like those in foods and the gastrointestinal tract, pose survival challenges.
- The bacterium utilizes an adaptive acid tolerance response (ATR) for low pH survival.
Purpose of the Study:
- To investigate the mechanisms Listeria monocytogenes employs to survive acidic conditions.
- To understand the role of specific acid resistance mechanisms, particularly the glutamate decarboxylase system.
Main Methods:
- Review of existing studies on Listeria monocytogenes acid resistance mechanisms.
- Analysis of mutant studies focusing on the glutamate decarboxylase system's protective effects.
Main Results:
- Listeria monocytogenes employs multiple strategies to combat acid stress, including the LisRK system, SOS response, σ(B) regulon, membrane fluidity changes, F0F1-ATPase, and enzymatic systems.
- The glutamate decarboxylase system provides significant protection in various acidic foods (juices, yogurt, dressings) and the stomach.
- The interplay and overlap of different acid resistance mechanisms require further investigation.
Conclusions:
- The glutamate decarboxylase system is a key factor in Listeria monocytogenes acid resistance in food and during gastrointestinal transit.
- Further research is needed to elucidate the effectiveness of other acid resistance mechanisms in relevant environments.
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