Study On The Mutation Breeding And Fermentation Technology Of The Neutral Protease-producing Strain AS1.398

In this paper,take AS1.398 Bacillus subtilis as the starting strain,firstly,the strains were induced by ultraviolet radiation,plasma and ⁶00 Co-?rays respectively,and then select the better mutagenic effects of plasma and 60Co-gamma rays to make compound mutation in order to obtain a ICo 16 strain which was induced⁶00 Co-?rays after plasma and produced the highest production of neutral protease.Through single factor and response surface analysis and other experimental means,the culture medium of the mutant strain was optimized.The best carbon source single factor obtained is corn flour and sweet potato powder,the best nitrogen source was soybean flour and bran.The optimal fermentation medium combination of response surface method:total carbon source?corn mixed with sweet potato powder as the ratio of 1:1?content was 5.20%,total nitrogen sources?soybean flour mixed with bran as the ratio of 1.8:1?was 5.18%,phosphate mixture?Na₂HPO₄ 0.45%mixed with KH₂PO₄ 0.045%as the ratio of 10:1?was 5%.Through single factor and orthogonal experiment,obtained the optimal fermentation conditions to induce strain:the weight of the four factors affecting the fermentation as the order of temperature>pH>inoculation volume>rotation rate,the optimum fermentation parameters were:take the temperature was 32?,take the pH was 6.9,take the inoculation volume was 3.5%,take the rotation rate was 220 r/min,which was similar to the results of single factor.After the company in the large-scale production of fermentation,the production unit of enzyme is higher than the current level of 20%,which means the highest enzyme production capacity of up to 12.6*103 U-mL^-1.