FIG 1.

A manL mutant of S. sanguinis SK36 had enhanced viability in stationary cultures. (A and B) Wild-type strain SK36 (MMZ1612), the manL mutant, and the complemented derivative of manL (manLComp) were (n = 3) cultivated for 20 h in BHI before being diluted into fresh BHI (A) or a TY medium containing 20 mM glucose (TYG20) (B), followed by growth monitoring in a Bioscreen system. For another set of SK36 samples (SK36 + Kp), 50 mM potassium phosphate buffer (pH 7.2) was added to the overnight cultures. (C) An in vitro sugar phosphorylation assay (measuring oxidation of NADH) was carried out using SK36 and manL mutant cultures prepared with BHI medium and harvested at the exponential phase. (D) For measurements of lactate, overnight cultures were diluted into TY containing glucose (Glc) or lactose (Lac), and the supernatants were harvested at the exponential phase. The results are the averages of three biological replicates, with error bars denoting standard deviations. Asterisks represent statistical significance according to Student’s t test (*, P < 0.05; **, P < 0.01; ***, P < 0.001).