Figure 2.

(A) Growth-dependent synthesis of EPS. The strains were grown in CPG medium to different cell densities. Cultures of wild-type strain DC283 (—┘—), strain ESN51 (-–-✳-–-), strain ESΔR (---⋄---), and ESΔIR (... ...) were analyzed for the presence of bound and free EPS. The data points indicated for each strain are the combined data obtained from three separate experiments. The amount of EPS (y axis) is expressed as pg/cell. The number of colony-forming units (CFU), expressed as Log₁₀ cfu/ml, was determined by dilution plating on nutrient agar. (B) Qualitative analysis of EPS production on nutrient agar medium (Left) and CPG medium (Right). The wild-type strain DC283 exhibits a mucoid phenotype only on CPG medium, whereas the ΔesaR and ΔesaIR mutants, ESΔR and ESΔIR, are mucoid on both media. The mutant strain ESN51 is unable to synthesize EPS under either condition.