Regulation of the glutamate-dependent acid-resistance system of diarrheagenic Escherichia coli strains. 2003

Arvind A Bhagwat
Produce Quality and Safety Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, Bldg. 002, 10300 Baltimore Avenue, Beltsville, MD 20705-2350, USA. bhagwat@ha.ars.usda.gov

The ability to withstand an acid challenge of pH 2.5 or less by Escherichia coli strains is a trait generally believed to be restricted to their stationary phase of growth. Of the three distinct acid-resistance systems that have been identified in E. coli, the glutamate-dependent acid resistance (GAD) system provides the highest level of acid resistance. Earlier reports indicated that in the exponential growth phase of E. coli K-12 strains the GAD system is not active. The present study reports that when grown on minimal medium several diarrheagenic and K-12 strains of E. coli have a complete set of induced genes necessary for GAD in the exponential growth phase to overcome the acid challenge of pH 2.5 for several hours. A previously identified factor(s) specific to the GAD system in the stationary phase and predicted to undergo dilution during the exponential phase appears to be glutamate-decarboxylase isozyme(s) inactivated differentially in the rich vs. minimal growth media.

UI MeSH Term Description Entries
D003470 Culture Media Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN. Media, Culture
D003967 Diarrhea An increased liquidity or decreased consistency of FECES, such as running stool. Fecal consistency is related to the ratio of water-holding capacity of insoluble solids to total water, rather than the amount of water present. Diarrhea is not hyperdefecation or increased fecal weight. Diarrheas
D004926 Escherichia coli A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc. Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000143 Acids Chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. (Grant & Hackh's Chemical Dictionary, 5th ed) Acid
D015964 Gene Expression Regulation, Bacterial Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria. Bacterial Gene Expression Regulation,Regulation of Gene Expression, Bacterial,Regulation, Gene Expression, Bacterial
D018698 Glutamic Acid A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM. Aluminum L-Glutamate,Glutamate,Potassium Glutamate,D-Glutamate,Glutamic Acid, (D)-Isomer,L-Glutamate,L-Glutamic Acid,Aluminum L Glutamate,D Glutamate,Glutamate, Potassium,L Glutamate,L Glutamic Acid,L-Glutamate, Aluminum

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