Ca2+ and Cu2+ supplementation increases mannitol production by Candida magnoliae

Supplementation with CaCl2 center dot 2H(2)O (50 mg l(-1)) or CuSO4 center dot 5H(2)O (10 mg l(-1)) improved mannitol production by Candida magnoliae by 14.5 and 18.6% (25 and 32 g/L), respectively. When used in combination, they acted synergistically: Ca2+ decreased the intracellular concentration of mannitol 30%, whereas Cu2+ increased the intracellular activity of mannitol dehydrogenase 1.6-times more than control. Ca2+ probably works by altering the permeability of cells to mannitol, whereas, Cu2+ increases the activity of an enzyme responsible for mannitol biosynthesis.