TY - JOUR
T1 - Comparison of the glutamate-, arginine- And lysine-dependent acid resistance systems in Escherichia coli O157:H7
AU - Diez-Gonzalez, Francisco
AU - Karaibrahimoglu, Y.
PY - 2004
Y1 - 2004
N2 - 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.
AB - 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.
KW - Acid resistance
KW - Arginine decarboxylase
KW - Enterohaemorrhagic
KW - Food-borne pathogen
KW - Glutamate decarboxylase
KW - Lysine decarboxylase
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U2 - 10.1111/j.1365-2672.2004.02251.x
DO - 10.1111/j.1365-2672.2004.02251.x
M3 - Article
C2 - 15139915
AN - SCOPUS:2542580836
SN - 1364-5072
VL - 96
SP - 1237
EP - 1244
JO - Journal of Applied Microbiology
JF - Journal of Applied Microbiology
IS - 6
ER -