FIG. 8.

Activation of the betaine uptake system in L. lactis NCDO763 as a function of NaCl concentration. Wild-type cells were grown in CDM (○) or CDM–0.3 M NaCl (●) containing 1 mM betaine. Cells were harvested (OD₆₀₀ = 1 to 1.5), washed twice, and resuspended in 50 mM MES-NaOH (pH 6.5) containing 0.5% glucose and 50 μg of chloramphenicol per ml. After 5 min of preincubation at 30°C, uptake was initiated by the addition of 20 μM [1-¹⁴C]betaine (specific activity, 2.5 mCi/mmol), and NaCl final concentrations and initial rates of betaine uptake were determined as indicated.