Primary Studies On Fermentation Condition Optimization Of A2-Strain And Separation Of Antinomycete Ingredientsfrom The Fermentation Broth

Actinomycete strain- A2 was isolated from the water of Bo Hai by pesticide institude of Northwest A&F University.The earlier stage study results showed that the fermentation extracts had a high fungicidal activity agaist mycelium growth or spore germination of Botrytis cinerea,Fusarium raminearum, Alternaria longipes, Fusarium solani, Curvulavia lunata.This dissertation was focused particularly on studies on fermentation condition optimization , extraction and purification .The main results were as follows:(1)The fermentation conditions of A2-strain were studied .The results of single factor and orthogonal experiments indicated that optimal carbon source was 1% cornmeal ,and 1% millet,the optimal nitrogen source was 0.3% peptone ,the opimal fermentation time was 120 hours,the opimal cultivation temperature was 28℃,and most suitable volume of cultivated liquid in 250ml conic bottle was 60ml.(2)The fermentation extracts from strain- A2 were ascribed to basic and water-solubable by meas of Jack's Eight Solvent System Chromatography and pH Paper Chromatography. TLC spray reagents indicated that it might containe the composition of alkal.oid components.Due to all qualitative analysis tests above ,It was proposed that crude products might be aminoglycoside antibiotic.(3)By means of 724 ion exchange chromatography and deposition,ion preparative HPLC,three compounds,H2,H3,H3,were isolated from fermentation of A2-strain .On the basis of spectral technology(MS,1H-NMR,13C–NMR),and compared with related literatures, H2 ,H4 were identified as streptothricin D and streptothricin F,respectively.(4) By means of spore germination and agar diffusion method, the results of bioassay showed that compounds,H2,H3,H4 had the high fungicidal activity agaist Exserohilum turcicum, Fusarium solani,Botrytis cirereaEscherichia coli , Bacilluscereus , Staphylococcus aureus and Bacillus subtilis.The results also showed that H4 had the highest fungicidal activity agaist Botrytis cirerea,and the EC50 was 56.99μg/ml.Under the concentration of 50mg/l by means of agar diffusion method, the diameters of inhibition zone against Escherichia coli , Bacilluscereus , Staphylococcus aureus , Bacillus subtilis were more than 7mm, respectively .