Study On The Production Of Cellulase Soluble Inducer And Its Fundamental Application In Cellulase Production

Cellulose in insolvable solid state is commonly used as carbon source and inducer for cellulase production,which results in some problems such as strong mass transfer resistance,unsuitability for fed-batch fermentation and low-yield production.In this work,a soluble inducer for cellulase production was obtained from glucose by the transglycosylation of glucosylase.It was found by High Performance Liquid Chromatography that the mixture derived from glucose by glucosylase contained sophorose which is a kind of strong inducer for cellulase production.When 300～500 mg·mL^-1glucose was treated with 8 IU free glucosylase at pH 4.0, 50℃for 100 h,the concentration of sophorose could reach 50 mg·mL^-1.And when 300～500 mg·mL^-1glucose was treated by 4 IU(5g)immobilized glucosylase at pH 5.0,55℃for 72 h,the concentration of sophorose reached 20 mg·mL^-1.Comparing to the free glucosylase,the continually releasing immobilized one had stronger tolerance to environment,and could be reused for more than 7 times.The glucose-sophorose mixture was used both as carbon resource and inducer for cellulase production by Trichoderma reesei in batch process.The culture media with 1.5%mixture(measured as reducing sugar)reached 50 mL in 250 mL container. Then cultivated the strain in 180 r·min^-1shaking incubation at 30℃,pH 4.8.The cellulase could be detected in 5 h,which was 25 h earlier than that of using glucose as carbon resource,while 7 h earlier than that of using MCC as carbon resource.The filter paper activity reached 1.8 IU·mL^-1at 60 h,which was 14 times higher than that of using glucose as carbon resource.Supplied the cultured media with glucose-sophorose mixture from 16 h to maintain reducing sugar concentration at 2～10 mg·mL^-1before 72 h and 1 mg·mL^-1after,thus leading to continually increasing cellulase activity.The results suggest a new approach for enzymatic preparation of soluble inducer for cellulase production,which is meaningfull in enhancing the efficiency of cellulase production and accelerating the application of cellulase in bioethanol production.