FIG. 2.

Growth analysis of tarK and tarL mutants. (A) S. aureus parent strain SA178R1 (EBII16) and ΔtarK (EBII100) and ΔtarL (EBII101) mutant strains were grown on MHA overnight at 37°C in the absence of complementation. Growth was assessed after 24 h. On solid medium, no discernible growth difference was observed for either mutant compared to the parent strain. (B) Growth of ΔtarK (▵) and ΔtarL (□) deletion strains and of parent strain SA178R1 (○) was also assessed in Mueller-Hinton broth. Each of these strains was subcultured to a starting optical density at 600 nm (OD₆₀₀) of 0.002, and growth was monitored by measuring the optical density at 600 nm from a 96-well plate in triplicate at 37°C, with aeration, at 250 rpm. Both mutants showed similar lag times before exponential growth. The tarK mutant showed comparable exponential growth to the parent strain, while the tarL mutant showed a slightly lower rate of growth during this stage. Although there was a slight slow-growth phenotype, neither mutant appeared to be compromised on either liquid or solid medium.