Optimization of mycelial biomass and protease production by Laccocephalum mylittae in submerged fermentation

Laccocephalum mylittae is a traditional Chinese medicinal fungus. Its wild sclerotium has been used in anthelmintic therapy for many years. Previous studies revealed that the main pharmaceutical component for the anthelmintic function of L. mylittae is an intracellular neutral protease, isolated from the wild sclerotium of this fungus. In this study, the mycelial biomass and protease production by L. mylittae in submerged fermentation was optimized using response surface methodology (RSM) and orthogonal matrix method. Under the optimum medium and conditions, the maximum activity of the anthelmintic protease from the mycelia of L. mylittae reached 4557.22 +/- 147.36 U per gram mycelial dry weight (U/g), with the biomass of 11.65 +/- 0.33 g/l after 3 d batch fermentation in a 15 l fermenter. This is a 2.71-fold and a 3.32-fold increase in protease productivity and biomass yield respectively, compared with that in the initial un-optimized fermentation process. The production time was also reduced from 4.5 d to 3 d. In addition, protease activity from the mycelia in optimized fermentation is 8.14-fold higher than that from the wild sclerotium of L. mylittae. These results provided valuable information for the further industrial production and applications of this fungus as well as its main pharmaceutical component.