Figure 1
From: L-glutamine provides acid resistance for Escherichia coli through enzymatic release of ammonia
Gln markedly enhances survival of E. coli under acid shock of pH 2.5. (A) A schematic diagram of an acid resistance assay. Upon inoculation into buffered LB medium supplemented with 0.4% glucose (to suppress AR1), E. coli was grown overnight to reach stationary phase. The culture was diluted 1:100 into EG medium, pH 2.5, supplemented with a specific amino acid. 2 h later, cells were checked for viability on LB agar plates. (B) Only Glu and Gln provide strong resistance to the acid shock. Approximately 30% and 25% E. coli survived with Glu and Gln as the amino acid supplement, respectively. Survival percentage was below 0.5 for any other amino acid. The results shown are the average of three independent experiments, with the SDs indicated.
