Screening Of Anti-MASA Bioactive Actinomycetes From Bawangling And Fermentation Optimization Of Strain Gda0301 And Gda0305

In this study, researches were carried out systematically on following aspects: isolation of actinomycete, screening and identification of anti-MRSA strains, optimum fermentation conditions and media of Gda0301 and Gda0305, and so on.A total of 287 actinomycetes were isolated from the soil samples of Bawangling on Gause No.1 medium(GAU)containing 0.005% K2Cr2O7 . Using Methicilin–resistant Staphyloccus aureus(MRSA)as model strain, 35 bioactive strains were obtained by the method of Kirby Bauer from 287 strain actinomycetes. Two strains, Gda0301 and Gda0305, whose anti-MRSA activation were very strong and high genetic stabilization were obtained by further screening, which were choosed as target strains for the deeper research.By studying the morphology,cultural characteristics,physiological and biochemical propertices,16S rDNA and phylogenetic tree, Gda0301 was proposed as Streptomyces griseovariabilis subsp. Bawangling, Gda0305 maybe a novel strain of Streptomyces, and more research should be carried out by DNA-DNA hybridization.The best optimal liquid fermentation conditions and media of Gda0301 and Gda0305 were obtained. The optimum culture media of Gda0301 contained sucrose 1.0%, dissolubile starch 1.5%, soybean powder 0.5%, yeast extract 1.0%, K2HPO4 0.05%; The optimum inoculation conditions of Gda0301were initial pH7.0~7.2, seed cultural time 48h, 12% inoculation amount, 28℃, 200r/min, 6d. Based on the optimized conditions, the optimum culture media of Gda0305 contained sucrose 1.5%, dissolubile starch 1.5%, soybean powder 0.5%, yeast extract 0.5%, K2HPO4 0.075%; The optimum inoculation condition of Gda0305 were initial pH7.0~7.2, seed cultural time 60h, 10% inoculation amount, 28℃, 200r/min for 6d.