FIG. 3.

Impaired growth of S. pneumoniae R6 strain EL1387 containing a regulated replacement of clpX (ΔclpX P_fcsK::clpX⁺) on medium lacking fucose. (A) EL59 (clpX⁺ parent), EL1383 (regulated merodiploid clpX⁺ P_fcsK::clpX⁺), and EL1387 (regulated replacement ΔclpX P_fcsK::clpX⁺) were streaked onto TSA-BA plates containing 0.25% (wt/vol) fucose (inducing) or lacking additional fucose (noninducing). Plates were photographed after 24 h of incubation at 37°C in an atmosphere of 5% CO₂. (B) EL1387 (regulated replacement ΔclpX P_fcsK::clpX⁺) was grown statically overnight in BHI broth containing 0.1% (wt/vol) fucose at 37°C in 5% CO₂. Cultures were then diluted 100-fold into fresh BHI containing or lacking 0.1% (wt/vol) fucose, and static incubation was continued at 37°C in 5% CO₂. Filled circles and squares represent the optical densities and viable cell counts, respectively, of the culture containing 0.1% (wt/vol) fucose. Open circles and squares represent the optical densities and viable cell counts, respectively, of the culture lacking fucose (0.001% [wt/vol]) carryover fucose from starting culture). Results are representative of at least two independent experiments. OD₆₂₀ (1.4 cm), optical density at 620 nm for a tube with a 1.4-cm diameter.