FIG. 4.

Levels of expression of various clusters of genes encoding proteins involved in amino acid metabolism in chemostat cultures of wild-type S. mutans (GS-5) and ΔglnR mutant. Specific primers for each gene were used in the RT-PCR. The means and standard deviations of the change in expression (fold change for expression of the gene in bacteria grown at pH 5.5 compared to expression of the gene in bacteria grown at pH 7.5) were calculated and listed below the blots as described in the legend to Fig. 3.