Aspergillus carneus M34 聚木糖酶特性分析、最適化固態發酵生產條件與其應用於木寡醣生產之探討

Abstract

Xylanase production strain, Aspergillus carneus M34, which was isolated from soil by our laboratory, was used to study the growth condition for optimal xylanase production, extraction methods and enzyme characterization by solid state fermentation used coba husk and corn steep liquor for the medium. In addition, possibility of the crude enzyme degrading coba husk hemicellulose to produce xylooligosaccharides was evaluated. Solid-state was the better fermentation type to ferment coba husk for xylanase production of Aspergillus carneus M34. In one factor test, the better cultivation conditions as follows: inoculums size 106 spores g-wm-1, cultivation temperature 25℃, initial pH value of medium pH 8.0. For optimization of the cultivation conditions, central composite design and response surface methodology were practiced. The optimal cultivation conditions were 25.6℃ of cultivation temperature, initial pH value of medium pH 7.96, the predicted maximum xylanase activity under optimal conditions was 6,781 U gdm-1. This represented 3.9-fold gain in xylanase activity. The better extraction conditions as follows: extraction temperature 25℃, extraction time 1 hour, pH of extractive pH 5.0 ~ 6.0, Tween 80 concentration of extraction solution 0.1%. The test of crude enzyme degradation of coba husk hemicellulose. The optimal pH and temperature were pH 5.0 and 50 ~ 60℃, respectively. It also exhibited a good pH stability at range of pH 4.0 to 7.0. In respect to thermostability, the residual activity of xylanase activity was 80% at 50℃ for 70 min. The crude enzyme hydrolyzed product contented xylooligosaccharides. The predicted xylooligosaccharides yield pre kg coba husk were xylobiose 61 g, xylotriose 11 g and xylotetraose 22 g under 30 min reaction.