Breeding Of The Heat-resistant Strain For Keratinase And Preliminary Study Of Its Fermentation

Keratin is a fibrous protein in connective tissue and the protective function,widely exist in the organizational structure of a variety of animal hairs, scales, hoofand angle. After treatment，keratin can be applied to all aspects of agriculture, industry,food industry and environmental governance. Keratinase is a specific degradation ofkeratin inducible enzymes, can be caused by bacteria, actinomycetes and fungi andother microorganisms to induce. As a result of keratinase in mild conditions andefficient decomposition of keratin and other proteins, to avoid the physical chemicalmethods to produce adverse effect, has important application prospect.The subject according to physiological characteristics of the production ofkeratinase strains, selected the soil samples from the center of the livestock manureheap, and cultured in medium with feathers as sole carbon source and nitrogen sourceafter treatment， then screening keratinase production strains through the transparentcircle. Final get12keratinase production bacteria numbered1-12. The results ofcolony growth morphology microscopic and growth in the medium and the16s rDNAidentification and physiological and biochemical test show that the selected strains areBacillus subtilis. By further different gradient high-temperature screening, the obtainedstrains can grow at70℃and75℃normally. Process of the keratinase productionheat-resistant strain in shake flask conditions have been studied, including add thesubstrate，temperature, pH value, speed, carbon and nitrogen source and inoculum size.We can determine the inoculum size5%, incubation temperature28℃, speed200rpm,pH7.5, with corn starch as a carbon source and casein as the nitrogen source, add10g/L feather meal to get the most good keratinase production.