Research On The Mutation Breeding Of Flavomycin And Regulation Of Fermentation Techniques

Flavomycin was industrially produced by Streptomyces bambergiensis. This thesis focused on the research of strain breeding and conditions optimization of fermentation. Through the technology of nitrogen ion beam mutating microbe, the thesis got one high-yield strain which could increased the fermentation capacity greatly and optimized the consist of fermentation medium for shaking flask and industrial production.This thesis studied the mutagenic effect of the original strain through nitrogen ion beam. Through the mutation rate and lethality of different doses of nitrogen ion, the optimized injection parameter was determined: energy: 20³0 keV,100 2.6 1013 ions/cm2. Under the conditions, the positive mutation rate and lethality was 32% and 80% separately. By mutation, the strain form changed remarkably. We concluded that the strains with surface smoothing and no/little corrugated edges existed higher production capacity. By initial screening and two re-screenings, we found one strain named FLM-Ⅱ-185MCB with productivity increased to 136.88% and its heredity stability was stable.We made a test of the three kinds of important raw materials in the fermentation shake flask formulation for the high-yielding Flavomycin FLM-Ⅱ-185MCB. The result showed that the best formula was: corn steep liquor 0.5% ,bean powder 5.0% ,corn starch3.0% ,soybean oil 4.5%,starch gum 2.3%, FeSO₄·7H₂O 0.00004%, CoSO₄·7H₂O 0.0001%, CaCO₃ 0.5%,MgSO₄·7H₂O 0.05%,ZnSO₄·7H₂O 0.0002%, K2HPO₄ 0.01%,CuSO₄·6H₂O 0.0005%, organic silicon 0.02%,surfactant DF-103 0.6%。The most optimal fermentation conditions were as follows: fermentation temperature, 37℃; Inoculation number 10%; the shaking speed of shake flask 260r/min.The strain FLM-II-185MCB was carried out in 50L agitating fermenter, and the process control was gained by optimization. Reducing the initial soybean oil concentration of basic culture medium and feeding soybean oil batch were favorable for strain growth and reproduction at early stage. Meanwhile, the strain consumed more soybean oil, which resulted in potency increase by 11.54% compared to the initial strain. By adding sterile water, the oxygen concentration was increased, and the fermentation potency increased by 19.42%. During different fermentation periods, we used different aeration ratio to maintain oxygen concentration above 30%, which would save the cost and maximize the benefit.