Mutation Breeding And Enzymatic Characteristics Of Feather-degrading Strain

With the development of global graziery in recent years,by-products are produced inevitably,while harvesting the animal goods.Among them,chicken feathers alone reach millions of tons per year.Often,storage environment is highly required because of the attaching fat and meat.In areas without required ones,burning is applied to manege them.However,harmful gas would be generated together.In industry,strong oxidants participate in treating feathers,but amino acid denaturalized with such treatments.Also,this would cause secondary pollution to the environment.Nowadays environmental friendly biodegrading is becoming an attractive approach.Strain Amycolatopsis.sp BJA-103,genome information of which had been obtained,was treated by diethyl sulfate(DES)to screen mutant with higher feather-degrading rate.Mortality was calculated by comparing the amount of colonies between the 0 min'treatment CK and the gradient time treatments.The time corresponding to mortality of84.2% was decided as the very time for mutagenesis.3 steps of screening of applied.First,by adding excess amino acid into medium,mutants with nitrogen catabolite repression would be inhibited.Mutant library with higher protease yield was expected.Then,Mutants owning smaller hydrolysis halos in skim milk medium shall be removed.For they may represent low protein degradation capacity.Finally,feather-degrading rate was measured every 24 h,and feather-degrading curve was made.Thus,one mutant owning ability to degrade feathers more faster and more thorougher was obtained.Optimization of fermentation(fermentation time,fermentation temperature,fermentation p H,and inoculum)and enzymatic characteristics(reaction temperature,reaction p H,chemical reagents,metal ions,substrate specificity)was researched at last of the task.In this study,mutant code M973 was screened by feather-degrading screening.Feather-degrading rate of M973 was 65.29% in 48 h,owning a great increase from 12.82%of wild-type.144 h later,M973 degraded 90.06% feathers,while wild-type strain degraded only 79.24%.In the end,enzymatic characteristics research showed that the optimum temperature and p H was 70 °C and 11.Meanwhile,keratinase activity would be inhibited strongly by reagent PMSF.