Screening Of A Strain With High-yielding Chitosanase, Optimization Of The Enzyme Production And The Analysis Of The Product

A strain producing chitosanase was isolated from soil samples and identified as Metarrizium sp JHOl. It is the only one Metarrizium strain that can degrade chitosan reported so far. The optimal culture conditions for JHOl strain producing chitosanase were 24℃ inculbating temperature, medium pH6.5, 2% chitosan, 500ml fermentation flask containing 150ml medium, 1:0.5 ratio of carbon and nitrogen and 3% amount of inoculation. The chitosanase activity of fermented broth was 2.67U/ml when Trichoderma sp JHOl was inculated in flask under the optimal conditions at 56h. The chitosanase from Trichoderma sp JHOl is an inducible and secreting extracellular enzyme. The optimum temperature and pH were 60℃ and 5.0, respectively; and the chitosanase was stable in the pH range of 4.0-6.0 or temperature under 45 ℃. Increasing substrate concentration could accelerate the hydrolysis of chitosan and the optimum substrate concentration was 2.5%. The chitosanase producing by JHOl was a hydrolyzing specific enzyme. The protein content of the fermented broth was estimated by Coomassie brilliant blue staining and the specific activity of the fermented broth was 23.37U/mg. The chitooligosaccharides in the products was identified by the thin-layer chromatography and HPLC. The method of promoting the content of the high physiological activity products was discussed and the reaction condition was optimized with 5h , 1:50 ratio of enzyme and substrate.