Morganella, Providencia and Proteus strains were capable of surviving pH 2.0 for 1 h if glutamate was present. These strains did not have glutamic acid decarboxylase activity and the gadAB genes were not detected in any of these bacteria. When exposed to pH 2.0 acid shocks, the survival rate of these bacteria was significantly increased with glutamate concentrations as low as 0.3 mM in the acid media. Escherichia coli cells incubated at pH 3.4 consumed four times more glutamate and produced at least 7-fold more 7gamma;-amino butyric acid than Morganella, Providencia and Proteus strains. These results indicate that strains belonging to the Proteeae tribe might have novel glutamate dependent acid-resistance mechanisms.
Bibliographical noteFunding Information:
Funding for this project was provided by the Minnesota Agricultural Experiment Station. The authors thank Dr. John W. Foster (University of South Alabama College of Medicine) for providing E. coli EK227 and EF522 strains, Dr. Patricia Ferrieri for providing enterobacteria, and Dr. Kun-Ho Seo for providing Enterobacter sakazakii.
Copyright 2012 Elsevier B.V., All rights reserved.
- Acid Resistance
- Escherichia coli
- Glutamate Decarboxylase