Complex Mutagenesis Of Keratinose Degrading Strain With Ultraviolet Ray And Diethyl Sulfate

Reasonable processing and using of abundant feathers resources in our country, not only reduce the feather pollution of the environment, but also provide protein resources for the development of the social production and animal husbandry. Microbial degradation of feather keratin is economical and environment ally friendly, this method recently has received widespread attention. The most types of microbe that can degradation feather keratin isolated by now are bacteria, especially Bacillus.But the keratinase in most of them is far from the requirements of industrial applications. Microbial mutation breeding based on artificially induced mutations, has the advantages of fast, effective and simple method, so it is the most commonly used method in laboratory research and industrial production. Due to the extremely low cost of equipment, and the extremely simple experimental operation, Ultraviolet rays(UV) and microware irradiation has been using so far. The alkylating agent is the most commonly used in the Bacillus mutation breeding mutagen, and diethyl sulfate(DES) is one of the most commonly used alkylating agent. One mutagen mutation breeding method is often difficult to achieve the desired objectives, so we can use complex mutagenesis which mutagenesis methods have a synergistic effect.In this study, I get the best mutagenic conditions of NJQ3bacteria obtained by UV mutagenesis, microware irradiation and DES mutagenesis conditions, After180r·min-1constant temperature shaker culture at37℃for8～12h, the original strain is made into the bacterial suspension. The UV mutagenesis time is2min; the DES mutagenic conditions is that DES concentration is1.5μL/mL and the mutagenesis time is5min. Microwave radiation experiments, when mutagenesis time is from1to8min, the fatality rate is less than60%, therefore microwave radiation is not suitable as NJQ3Mutation Breeding methods. After screening and rescreening, the results show that the stability of strain selected from UV mutagenesis is poor, and that of DES mutant strains is much better. By screening of three indicators, that is, the keratin medium degradable circle, soluble protein content and degradation rate, The four strains screened out from UV mutagenesis turned to be normal when they had passaged three times; there are five strains screened out from DES mutagenesis, D3,one of the five still has a positive mutant after passaged three times. There is no nomutant strain screened out from the microwave mutagenesis.The UV mutagenesis time is2min, after180r·min-1constant temperature shaker cult-ure at37℃for8～12h, the original strain is made into the bacterial suspension. And the DES concentration is1.5μL/mL, the mutagenesis time is5min.By screening of three ind-icators, that is, the keratin medium degradable circle, soluble protein content and degradati-on rate, I get a mutant strains YB5, which can stable pass more than10generations forn15screening strains. The keratin medium degradation circle of YB5is1.20cm,37.08%higher than the original strain; it’s soluble protein content is3.84mg/L,160.23%higher; degrada-tion rate is49.2%, and a9.82%increased.