The Investigation On Keratinophilic And Cold-adapted Fungi In Some Regions Of China And Optimization Of Enzyme Production Conditions Of A Candidate Strain

Keratin was a kind of scleroprotein,which widely existed in the feather,hair,wool,nails and so on.The chemical structures of keratin were very stable and particular,and it is difficult to be degraded and applied.Moreover,keratin generally was insoluble and difficult to be degraded by the common protease.Therefore,discarding them randomly not only made the sources wasteful,but also caused the pollution of our environment.It was a good idea to degrade the keratin by using the microorganisms.The way to dealt with the materials containing keratin not only improved the environment,but also generated the nutritional value.The products through degrading those materials could be used in leather industry,cosmetic industry,detergent industry and other fields.Keratin and keratinase were suggested to be a kind of the valuable rescource and have the broad prospects for further development.The resources of keratinophilic cold-adapted fungi were extensively investigated and systematically studied.These results will not only enrich our strain resources data but also provide many valuable fungal resources for the biotechnology industries.The main results were as follows:1.The investigation and classification to the resources of keratinophilic cold-adapted fungi had been done in 8 different territories of China.3 strains of Geomyces,11 strains of Microsporum,7 strains of Chrysosporium,2strains of Scedosporium were isolated and identified from 530 soil samples,and there were 6 new species described and identified in the genus.2.61 strains of keratinophilic cold-adapted fungi were screened out by the medium based on the feather powder as the sole carbon source,A strain labelled as G79 with high capability of keratinase production was obtained by degradation rate of feather secondly in submerged medium.Morphological study and phylogenic analysis based on the ITS1-5.8S-ITS2 r DNA sequences have proved that the strain G79 was a new taxon of Scedosporium.3.In our experiment condition,simple factor design of experiment was studied.the complements of different C-sources,N-sources,S-sources,mineral ions,inoculum size,feather powder and initial PH in base medium were completed,respectively.The results showed that substrate with strongest promotor action were separately lactose,yeast extract,Sodium sulfate,Zinc sulfate,inoculum size 5%,feather powder 20g/L and initial PH 9.4.The regression equation of the model was established by Plackett-Burman design,Steepest ascent experiments,and Box-Behnken design.Y=5384-131.25X₂+292.5X₁+256.25X₅-2.5X₁X₂-195X₂X₅+262.5X₁X₅-894.5X₂²-427X₁²-394.5X₅²There was a stationary point for Y,while X₁=-0.133?X₂=0.222?X₅=0.222 namely,inoculum size58.67m L/L,feather powder0.44g/L,initial PH9.22,The prospective max value of keratinase activity was 5485.79U/L.The latter was 9 times higher than the keratinase activity in ferment using the basic medium.