Malolactic fermentation activity of S. sobrinus 6715 and S. mutans UA159 at pH 5.5 and pH 7. S. sobrinus and S. mutans cells were grown in TY broth (adjusted with HCl, pH 5.5 or buffered with potassium phosphate, pH 7), supplemented with 25mM glucose and 25mM L-malate until stationary phase. Cells were harvested, washed with salt solution, and resuspended with 50 mM L-malate. The results represent the means ± the standard deviation of three independent experiments. (*) P ≤ 0.05.