FIG. 3.

Assay of pantothenate uptake activity. E. coli strain DV1 (see the text and Fig. 1B for the genotype and phenotype, respectively) containing an empty vector (−) or expressing the L. mesenteroides genes indicated on the right was pregrown in β-alanine-containing mineral salts medium. Cultures were harvested and washed in sterile buffer. Aliquots of 10-fold serial dilutions were spotted onto mineral salts agar plates containing 1 mM IPTG and either no additional supplement, 1 μM β-alanine, or 1 μM Ca²⁺-pantothenate.