The production of erythritol and the erythritol yield from glucose by Torula sp. were improved, in increasing order, by supplementing with 10 mg MnSO4 . 4H(2)O l(-1), 2 mg CuSO4 . 5H(2)O l(-1), and both 10 mg MnSO4 . 4H(2)O l(-1) and 2 mg CuSO4 . 5H(2)O l(-1). Mn2+ decreased the intracellular concentration of erythritol, whereas Cu2+ increased the activity of erythrose reductase in cells. These results suggest that Mn2+ altered the permeability of cells, whereas Cu2+ increased the activity of erythrose reductase in cells.