Studies On Mutation Breeding,Fermentation Medium Optimization And Ultrafiltration Extraction Product Of ?-Polylysine Producing Strain

This experiment adheres to the principle of increasing the yield of?-polylysine.The?-polylysine-producing bacteria has been optimized for compound mutagenesis treatment conditions and the fermentation products have been initially identified,and the results are more economical and yield increased.A better carbon and nitrogen source and the application of response surface test to optimize the fermentation medium formula,and finally use ultrafiltration to extract the product and use activated carbon fiber for decolorization research.(1)Select No.2 Streptomyces albicans among the three strains of Streptomyces albicans for follow-up experiments.First,The compound mutagenesis conditions of Streptomyces albus No.2 were optimized by orthogonal test is UV After 7.5s of irradiation,15?L of DES and the same amount of 95%ethanol were added and shaken vigorously for 12 minutes.The concentration of?-polylysine in the fermentation broth of the strain mutagenized under this condition was 8.493g/L,compared with the original process,the yield of the product increased by 93.77%.(2)Both Dragendorff reagents and the supernatant of the fermentation broth of the mutagenized strain produced obvious precipitation,indicating that the fermentation broth contained alkaloids.It was further verified by liquid chromatography,and the results showed that the peak time of the strain fermentation broth after mutation was 2.450 min,which was very similar to the peak time of the?-polylysine standard product at 2.467 min,and the peak shapes were almost the same,Indicating that the alkaloids in the fermentation broth are very similar to?-polylysine.(3)The results showed that glucose,glycerol and molasses were selected as carbon sources,corn syrup and medium temperature soybean meal as the organic nitrogen source,and ammonium sulfate and chloride as the inorganic nitrogen source.Ammonium.(4)The results of composite carbon source and composite nitrogen source optimized by response surface test are:The concentration of composite carbon source is 4%,carbon source ratio is glucose:molasses=1:4,composite nitrogen source concentration is 1.5%,nitrogen source The ratio is ammonium chloride:corn steep liquor=1:2.The final fermentation medium formula is:glucose 8g/L,molasses 32g/L,ammonium chloride 5g/L,corn syrup 10g/L,Mg SO₄·7H₂O3.2g/L,Fe SO₄·7H₂O 0.08g/L,Zn SO₄·7H₂O 0.04 g,K₂HPO₄ 2.4/L,KH₂PO₄3.2g/L,the product yield is maintained at about 14.76 g/L under this fermentation medium condition.(5)Finally,the fermentation broth of this mutant strain was subjected to a decolorization test after ultrafiltration,and the activated carbon fiber model used for decolorization was screened.As a result,the bjrxyw-04 model was selected,and the decolorization rate was 91.12%,which was 5.46 higher than the decolorization rate of traditional activated carbon powder.%.The?-polylysine loss rate was 6.03%after the fermentation broth filtrate was passed through ultrafiltration and bjrxyw-04 activated carbon fiber decolorization.