FIGURE 8.

Comparison of transformation efficiency and sigX expression in S. mitis type strain and S. mitis strain SK321. (A) S. mitis type strain and SK321 pre-cultures at OD₆₀₀ 0.5 were diluted 1:100 in C+Y_{Y B} and grown until OD₆₀₀ 0.04 at 37°C in 5% CO₂. Following, 200 μL aliquots were exposed to 300 nM of their respective strain specific CSP or kept untreated. Cells were transformed with 1 μg mL^-1 replicative plasmid pVA838 at 37°C in air atmosphere for 3 h. The % of CFU containing Erm^R transformants was determined by plating on blood plates with and without Erm. The results are representative of three independent experiments. Bars represent standard error of the mean. Differences in efficiency between cultures with and without CSP were analyzed by Student’s T-test (^∗p < 0.05). (B) The sigX reporter type strain (MI055) and SK321 (MI092) were grown in 200 μL of C+Y_{Y B} in a 96-well plate in air at 37°C with 300 nM of their respective strain specific CSP or kept untreated. Culture optical density (OD₆₀₀) and sigX expression (RLU/OD) were monitored periodically. The results are averages from three replicates and representative of three independent experiments. Error bars represent standard error of the mean.