The Screening Of Tylosin Producing Strain With High Yield And Fermentative Optimization For Streptomyces Fradiae

This paper made a comparison of four mutagenesis methods on advantages and disadvantages. EMS(0.25%)4h+UV45s was chose as the best method. Through shake flask screening, two stable high yield mutants were gained:EU45-15and EU45-42, compared with the original strain, tylosin yields were increased by15.36%and22.04%, respectively. Analyzed by HPLC, it showed that the percentage of the highest active component-A component of EU45-15and EU45-42were48.28%and38.9%respectively higher than that of control.On the basis of analyzing metabolic pathways of tylosin, three directed screening materials were used to screen high-producing strain of Streptomyces fradiae. We chose EU45-15as an initial strain, after screening by soybean oil, mutant03.6-8was selected. Its production of tylosin was increased by12.15%. The residual oil of O3.6-8was lower than that of control which showed preliminary that the activity of lipase in03.6-8was higher than control.Tylosin is a kind of macrolide antibiotics, acetic acid, propionic acid and butyric acid are its precursors, adding some short-chain fatty acids in the fermentation medium could improve the yield of tylosin. Therefore, four short-chain fatty acids, sodium acetate, sodium propionate, sodium malonic acid and sodium citrate were respectively used as supplements at the beginning of fermentation of EU45-15. It proved that sodium malonic acid had the most obvious promoting effect on the yield of tylosin. We also tested the timing of adding sodium malonic acid and found that adding sodium malonic acid(0.2%) after12hours of fermentation had the best effect, the increase of production was9.8%.Vitamin B can not only promote growth of cells but also promote activities of certain enzymes as cofactors, so the addition of Vitamin B in fermentation medium could promote synthesis of antibiotics. In this experiment, biotin, lipoic acid, calcium pantothenate and VB12were added at the beginning of fermentation of EU45-15, in addition to calcium pantothenate, the others can all improve the production of tylosin, we got the best promotion (8.1%) of the production of tylosin while the adding concentration of VB12was0.08mg/L.