Studies On Ganoderma Lucidum Laccase Production By Liquid Fermentation

Laccase (benzenediol : oxygen oxidoreductase, ECl.10.3.2 ) was a p-diphenol oxidase containing four Coppers. Researches on laccase were more and more attractive in recent years. Currently, most of the studies about fungal laccase were focused on a few species of fungi and there were few reports on Ganoderma lucidum laccase.Two different termination methods of Ganoderma lucidum laccase determination were compared in this paper. The results revealed that it was feasible to terminate the enzyme reaction by heat. Compared heating with freezing, the former was more reliable, repeatable, simple and convenient.The optimum culture medium and conditions in shaking flasks for laccase production by Ganoderma lucidum were studied. To measure Ganoderma lucidum laccase activity in different culture medium and conditions through orthogonal experiment, the optimum culture components were: Glucose 30.0 g/L, cotton 0.2 %, (NH₄)₂HPO₄ 0.66 g/L, casein 0.5 %, Tween-80 0.15 ml; after culture medium optimization, Ganoderma lucidum laccase activity of submerged fermentation liquid is 25.72 times as basic liquid medium; the optimum conditions were: initial pH of medium 5.5, 75ml medium in 250 ml-flask, inoculation 12.5 %, mycelium age 5×24 hr, culture time 9×24 hr. Ganoderma lucidum laccase activity of submerged fermentation liquid improved remarkably in the optimum culture and conditions, with 2.12 times as non-optimized culture conditions and 49.26 times as basic liquid medium.From the PAGE zymogram, it was inferred that Ganoderma lucidum laccase is a single enzyme and there was no other isoenzyme expressed in the process of liquid fermentation. The positive correlation between Ganoderma lucidum laccase activity and its production was revealed.The biosynthesis of Ganoderma lucidum laccase was facilitated in various extents by four metallic ions of Cu²⁺, Zn²⁺, Mn²⁺ and Fe²⁺. The effect of Cu²⁺ was the most, and its peak value was approximately 3.47 times as the control. The following was Mn²⁺,...