Primary Studies On Identification Of Actinomycete M10 And Separation Of Antimicrobial Ingredients From The Fermentation Broth

Actinomycete M10, isolated by institute of pesticide of Northwest A&F University, has been studied on strain identification, antimicrobial activity, metabolites stability, extraction and purification. The main results are as follows:1. The 16S rDNA sequence results showed that the homology between strain M10 and Streptomyces qinglingensis is 99%. However,the cultural,physiological and biochemical characteristics demonstrated that the strain are different to those of the model strain,so strain M10 is proposed as a close or the similar species of Streptomyces qinglingensis.2. By means of mycelium growth rate, the results showed that the fermentation broth of M10 had more than 90% inhibition rate against Fulvia fulvum, Alternaria alternata, Monilia fructigena, Valsa mali and Gibberella zeae. The results of spores'germination tests indicated that EC₅₀ of the fermentation broth of M10 were 72.99 mg/l, 79.11 mg/l and 44.52mg/l against Alternaria alternata, Fusarium coeruleum and Exserohilum turcicum, respectively. By means of agar diffusion method, the diameter of inhibition zone against Bacillus subtilis, Bacillus cereus, Escherichia coli and Staphylococcus aureus were 25mm,24mm,20mm and 25mm, respectively. Pot tests indicated that the fermentation broth of M10 exhibited 85.90% protective efficacy and 78.69% therapeutic efficacy against Erysiphe graminis. The field trails results showed that the control efficacy of the fermentation broth of M10 against Pseudoperonospora cubensis and Fulvia fulvum were 70.68% and 64.67%, respectively.3. The results of the stability test indicated that antimicrobial activity of fermentation broth had few variety when strain M10 was cultivated 10 generations seriately. And it was stable to acid, sunshine and light, but it was unstable to alkali and temperature. 4. The fermentation productivity of M10-strain may be ascribed to alkalescent and water-solubility antibiotic by means of paper chromatography and solvent extraction. By means of 732 ion exchange chromatography (NH₄⁺) and deposition, the crude crystal of antibiotic from M10-strain was gained. TLC spray reagents of phosphorus molybdenum acid and bismuth potassium iodide indicated that it maybe contained the composition of alkaloids. Due to all qualitative analysis tests above, we primarily proposed that the crude crystal of antibiotic contained aminoglycoside antibiotic.