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Comparison of the glutamate‐, arginine‐ and lysine‐dependent acid resistance systems in Escherichia coli O157:H7
Author(s) -
DiezGonzalez F.,
Karaibrahimoglu Y.
Publication year - 2004
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2004.02251.x
Subject(s) - lysine , arginine , escherichia coli , glutamate receptor , anaerobic exercise , glutamic acid , amino acid , biochemistry , lysine decarboxylase , biology , chemistry , enzyme , receptor , putrescine , gene , physiology , cadaverine
Abstract Aims: The objective of this study was to investigate the effect of growing conditions on the glutamate‐, arginine‐ and lysine‐dependent acid resistance (AR) systems of Escherichia coli O157:H7. Methods and Results: Seven E. coli O157:H7 strains were grown in five different media at neutral or acidic pH under aerobic or anaerobic conditions, and the survival rate after acid shocks (pH 2·0, 1 h, 37°C) in the presence of glutamate, arginine and lysine was determined. Six strains induced the glutamate‐dependent AR at stationary phase, and maximal survival were observed (≥10%) when grown in pH 5‐ Luria‐Bertani media with glucose (LBG) and in pH 4·5‐anaerobic media. The arginine‐ and lysine‐dependent systems were also present, but were only induced if cells had grown in LBG. For strain ATCC 43895, the minimum glutamate concentration that resulted in at least 10% survival rate was 10 μ mol l −1 , but it required at least 10‐fold more arginine and lysine. Conclusions: The lysine‐dependent AR system could be as important as the arginine‐mediated one, but the contribution of both systems to E. coli O157:H7 overall AR response might be minor compared with the glutamate‐dependent system. Significance and Impact of the Study: Under typical environmental conditions, the glutamate‐dependent AR system might be solely responsible for protecting cells against acidic pH.