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With the growing problem of antibiotic resistance, there is an urgent need to find new antibacterial drugs. Ketolide antibiotic resistant role in dealing with prominent, is the most promising new antibacterial drugs. The the homologous recombination party has constructed the Saccharopolyspora Red molds M can synthesize a new keto esters - 3 - deoxy-3 - carbonyl - Erythromycylamine lactone B, however, lower yields, product no inhibitory activity. Mutagenesis by 60Co-Y-rays of Saccharopolyspora red mold M the the Saccharopolyspora red bred mold 963 and 967 although the product has antibacterial activity, but the yield is to be further improved. Usually the compound mutagenesis better mutagenic effects. 60Co-γ-ray of this experiment repeated Mutation Breeding respectively Saccharopolyspora red mold 963 and 967, in order to obtain high yield mutant. On the choice of the spore dilutions, respectively, with normal saline and 5%, 10%, 20%, 40% and 80% glycerol, appropriately diluted spore different dose irradiation (not the irradiated sample as a blank control), coated tablet, counted and calculated spore death rate, to select suitable spores dilution and appropriate irradiation dose; repeated mutagenesis treatment using the appropriate conditions to the spores, and combine a certain concentration of streptomycin the R3M resistance Flat filters mutant . Observation of morphological, take mutant was fermented liquid, Bacillus subtilis antibacterial test screening positive mutation calculated mutation rate study 60Co-γ ray repeat mutagenic effects on the Saccharopolyspora red mold 963 and 967. To explore the streptomycin resistance screening methods to the Saccharopolyspora red mold 963 as the research object mutant was screened at the same time using the in R3M tablet gradually improve streptomycin concentration. Determination streptomycin minimum inhibitory concentration experiment shows that with increasing streptomycin concentration of Saccharopolyspora red molds 963 and 967, inhibition enhanced. Plate when streptomycin concentration of 140μg/mL and 120μ, g / mL, respectively, no regeneration strains, the minimum lethal concentration. Fixed the streptomycin concentration Resistance screening method experimental selection of 130μg/mL and the 110μg/mL streptomycin resistant tablet mutant was screened; increase resistance to streptomycin concentration screening method experiments, sugar spore red mold 963 as an object of study, the concentrations from 130μg/mL increased 140μg/mL, 150μg/mL and 160μg/mL. Growth of irradiated spores by comparing saline and 5%, 10%, 20%, 40% and 80% glycerol and the experimental operability, and saline as the spore dilutions appropriate. The experiments show that the higher the radiation dose, the higher spore mortality. When the dose is 500Gy, Saccharopolyspora red mold spore death rate of 963 and 967 are about 90%, is selected as the best mutagenic doses. 60Co-γ sugar and more repeat Mutation Breeding spore red mold 963, a positive mutants significantly enhanced antimicrobial activity, genetic stability, positive mutation rate of 2.01% o; 12 morphological variation strains, sporulation time, spore color are changed greatly, morphological variation rate of 24.1% o. Compared with single mutagenic repeat mutagenesis get better results. Increased streptomycin resistance selection pressure screening experimental results show that compared with fixed selection pressure, although the morphological variation have been significantly improved, but generate excessive negative mutation rate is not conducive to effective screening. 60Co-γ ray supplemented by fixed streptomycin resistance selection pressure the screening the Saccharopolyspora red mold high yield mutant strains morphological variation and positive mutation rate can be significantly improved. Good genetic stability of the obtained mutant strain overcomes the mutagenesis random screening adventitious isotropic and blindness, and improve the working efficiency of breeding. The results of this experiment has laid the foundation for the further study of sugar and more red spore mold industrialized application.
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