The presence of 10 mg/l zinc along with other nutrient
supplements in the fermentation medium of wood
hydrolyzate increased the rate of sugar utilization when
compared to the absence of zinc (Fig. 2(a) and (b))
(P =0.02). The increase in ethanol production caused
by the addition of zinc was probably due to high activity
of zinc-dependent alcohol dehydrogenase (ADH) in the
fermentative pathway. ADH has been extensively studied
in Saccharomyces cerevisiae, where it occurs as four
isozymes and has been found to be zinc dependent
(Hahn-Hagerdal et al., 1994; Jornvall et al., 1987).