NOVELTY - Preparing mutagenized strain involves departing Bacillus subtilis from prawn breeding pond bottom sediment. The obtained Bacillus subtilis is cultured, mutagenized and inoculated into medium. Fermentation is carried out for 6 hours. The fermented product is centrifuged to obtain precipitate, which is washed with sterile saline and diluted. Optical density is measured at 600nm after 5-fold value 0.6-0.8. The diluted broth (10 mu l) is added to special metal sheet using plasma at atmospheric pressure at room temperature to carry out strain mutagenesis.    USE - Method for preparing mutagenized strain for processing waste (claimed).    ADVANTAGE - The method enables to prepare mutagenized strain with high protease activity that is utilized in protein degradation and animal feed industry.    DETAILED DESCRIPTION - Preparing mutagenized strain involves departing Bacillus subtilis from prawn breeding pond bottom sediment. The obtained Bacillus subtilis is cultured, mutagenized and inoculated into medium. Fermentation is carried out for 6 hours. The fermented product is centrifuged to obtain precipitate, which is washed with sterile saline and diluted. Optical density is measured at 600nm after 5-fold value 0.6-0.8. The diluted broth (10 mu l) is added to special metal sheet using plasma at atmospheric pressure at room temperature to carry out strain mutagenesis. The sample form the slide is removed and incorporated with sterile saline tube (1ml) and shaken to make it completely suspended in saline and diluted with saline. The diluted material (100 mu l) is applied to filter plate for generating colonies with circle diameter ratio. Plasma positive mutagenic mutant strains are screened on the plate. The screened strain are inoculated in culture medium for overnight. Inoculum (1%) is transferred to fermentation medium and fermented for 15 hours at 12000 revolutions per minute for 3 minutes. The obtained supernatant is crude enzyme solution with high activity strains. The obtained high activity strains are filtered out and inoculated into the plate under ultraviolet light irradiation for 5-10S. Process is repeated again for screening high activity strains. The obtained positive mutants are screened and continuously passaged for 10 times to obtain better genetic stability of resulting strains.