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The test from 120 actinomycetes room flat confrontation antagonism measured to get the rice blast fungus strains of varying degrees of antagonism 4 (St-10, St-85, St-107, St-120), where St-10 strain of the rice blast fungus showed strong antagonistic activity, to confront culture The antibacterial bandwidth 11.3mm, the fermented liquid antibacterial bandwidth is 7.8mm relative inhibition rate of 52.0%. St-10 strain 16SrDNA full sequence analysis, and the results show that the St-10 strain with rising island chain mold (Streptomyces capoamus) sequence identity of 98%, of St-10 strain of morphological characteristics, cultural characteristics and physiological and biochemical characteristics Classification and Identification, (Streptomyces sp.) gray the purpurin taxa (Griseorubroviolaceus) of the ST-10 strain belongs to the Streptomyces genus. St-10 as the original strain, ultraviolet (UV) and 60 Co mutagenic treatment, initially clear the strain mutagenic treatment ultraviolet irradiation time 40s, 60 Co optimal treatment dose for 60,000 gamma-roentgen. St-10 strains, ultraviolet radiation treatment, screening and rescreening higher levels of production of antibiotics mutant strain U-5; U-5 strain the conduct 60 Co. irradiation treatment after screening and rescreening get a good genetic stability of the mutant strain C-18, 52.4% of the starting strain of its relative antibacterial rate increased to 73.5%, 1.4 times the original strain. Produce antimicrobial substances antagonistic bacteria C-18 fermentation medium, initial pH, temperature, speed, loaded fluid volume and incubation time factors fermentation condition of a preliminary study. Studies have shown that the C-18 strain suitable fermentation medium is the QH medium: soybean flour 20g, starch 50g, NaCl, 2g, K 2 HPO 4 1g, CaCO , 3 5g, water 1000ml. Suitable flask fermentation conditions: initial pH value of 7.5, shaking the bottled liquid volume 50ml/250ml flask fermentation temperature of 32 ° C, shaking speed 160r/min, fermentation time 8d. Fermentation conditions orthogonal test results showed that the pH affect the fermentation broth of rice blast fungus antibacterial activity of the main factors, the most obvious impact of liquid loading four factors in order for the pH> to culture time> temperature> installed fluid volume. Optimum fermentation conditions, the relative inhibition rate of 88.2%. C-18 strains fermentation broth pH stability and thermal stability studies have shown that the antibacterial activity of the fermentation broth in a weak acid, weak base and neutral environment stable, extremely acid and alkali environment activity is easy to lose, when The highest activity at pH = 7.5; antibacterial activity and stability in the environment of 75 ° C and 100 ℃ environment activity declining with time.
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