Figure 3. Growth curves of the parental B. melitensis strain 16 M, its otpR mutant 16 MΔotpR, and the mutant complementation strain 16 McΔotpR in a synthetic minimal medium.

The minimal medium contains only carbon and nitrogen as the nutrient resources. Compared to the wild type strain, the otpR mutant had a decreased OD600 value. The gene complementation of the otpR mutant resumed the OD600 level. A curve of the optical density values at OD600 determined at several time points reflects the growth dynamics of a bacterial strain in the culture medium over the different time points.