Regulation of Sugar Transport Systems in Fusarium oxysporum var. lini.

Fusarium oxysporum var. lini (ATCC 10960) formed a facilitated diffusion system for glucose (K(s), about 10 mM) when grown under repressed conditions. Under conditions of derepression, the same system was present together with a high-affinity (K(s), about 40 muM) active system. The maximum velocity of the latter was about 5% of that of the facilitated diffusion system. The high-affinity system was under the control of glucose repression and glucose inactivation. When lactose was the only carbon source in the medium, a facilitated diffusion system for lactose was found (K(s), about 30 mM).