Regulation Mechanism And Induction Expression Of Xylan Degrading Enzymes In Volvariella Volvacea

Hemicellulolytic microorganisms play a significant role in nature by recycling hemicellulose. The edible straw mushroom, V. volvacea, Cultured on cellulosic wastes could turn cellulose or hemicellulose into value-added food sources. These characteristics indicate that V. volvacea has a whole series of cellulolytic and hemicellulolytic enzymes. In this paper we cultivate V. volvacea in the media with different carbon sources and nitrogen source, investigating the effects of different carbon sources and nitrogen sources on hemicellulase production and the regulation mechanism of action of hemicellulase.1. In V. volvacea hemicellulases such as xylanase,β-xylosidase,arabino- furanosidase,glucuronidase,acetyl esterase are inducible. The major inducer is the corresponding carbon-source. Cultured on glucose,MC,cellobiose,filter paper,xylan,straw,bran,corn core, the optimal inducer for xylanase is straw ,and the enzyme had the highest activity of 0.623 IU/ml on 8 day. Cultured on filter paper,xylan,straw,corn core, the optimal inducer forβ-xylosidase is xylan, and the enzyme had the highest activity of 0.261 IU/ml on 8 day. Cultured on MC,cellobiose,filter paper,xylan ,the optimal inducer for arabinofuranosidase is filter paper, and the enzyme had the highest activity of 0.488 IU/ml on 12 day. Cultured on xylan,straw,corn core, the optimal inducer for glucuronidase is xylan, and the enzyme had the highest activity of 0.325 IU/ml on 10 day. Cultured on glucose,MC,cellobiose,filter paper,xylan,straw,bran,corn core,the optimal inducer for acetyl esterase is corn core, and the enzyme had the highest activity of 0.648 IU/ml on 8 day. The expression level of acetyl esterase is lowest on glucose.2. In V. volvacea the expression of the hemicellulolytic enzymes is regulated by inducers and growth cycle on transcription and translation level. Semi-quantitative RT-PCR showed: the mRNA of xylanase from V. volvacea which were cultured on MC had the highest transcription level on 10 day. The mRNA of xylanase from V. volvacea which were cultured on glucose,glycerol,xylan,CMC,cellobiose had the highest transcription level on xylan. And the transcription level of xylanase is lowest on glucose.3. The optimal pH and temperature conditions for xylanase were 7.5 and 50℃,β-xylosidase 4.0 and 50℃,glucuronidase 5.0 and 50℃,galactosidase 6.0 and 50℃,arabinofuranosidase 6.0 and 50℃.