The Research On Effects Of Carbon And Nitrogen Resource On Zhongshengmycin Production

Zhongshengmycin was biosynthesized by Streptomyces lavendulue var. Hainanensis, which is a type of N-glycoside agricultural antibiotics. In this work, I studied the effect of glucose and ammonium chloride on fermentation, and researched the influence of supplemented glucose and ammonium chloride on zhongshengmycin production in defined medium. 1. The development of defined medium used in this work After comparison of fermentation titer, I chose UV-69 as the Strain used in this work from several zhongshengmycin producing strain, such as UV-69, UV-66, UV-59, UV-27, UV-7, B-7. Sodium glutamate was chosen as the organic nitrogen source, and ammonium chloride was chosen as the inorganic nitrogen source in chemically defined fermentation medium. The orthogonal design method was adopted to select the optimum chemically defined fermentation medium. The optimum medium was obtained by variance analysis. 2. The effect of initial glucose concentration on fermentation in defined medium The results showed that initial glucose concentration drastically influenced the growth of Zhongshengmycin-producing strain. With the increase of initial glucose concentration, the growth pattern was changed. The growth rate increased during exponent phase, and higher biomass and longer biomass accretion were observed. When initial glucose concentration was 3.5% or beyond, zhongshengmycin production was repressed. It was suggested that active growth and longer biomass accretion in antibiotic peak producing stage might be the reason for zhongshengmycin production repression. 3. The effect of initial ammonium chloride concentration on fermentation in defined medium With the increase of initial ammonium chloride concentration in defined medium, lower biomass was observed, but fermentation titer was not influenced evidently. This result showed that higher ammonium chloride concentration could repress the growth of Zhongshengmycin-producing strain, but it could not repress zhongshengmycin biosynthesis. Contrarily, according to the comparison of specified zhongshengmycin production, it was suggested that ammonium chloride could promote zhongshengmycin biosynthesis. 4. The influence of supplemented glucose on zhongshengmycin production in defined medium The experiment results showed that supplemented glucose could promote zhongshengmycin production, and the promotion effect was mainly caused by the increase of biomass. Glucose supplemented between exponential phase and zhongshengmycin peak producing stage could improve fermentation titer largely. Before or after this phase, the improvement effect of supplemented glucose was slight. In addition, glucose should be supplemented many a time, and the quantity of supplemented glucose should be little at a time. 5. The influence of supplemented ammonium chloride on zhongshengmycin production in defined medium The results showed, if ammonium chloride was supplemented in exponential phase (1 2h), zhongshengmycin production would be improved drastically, but the growth of Zhongshengmycin-producing strain would be repressed. The hig1~er aninhonium chloride concentration was, the stronger the repression effect was. So, amxnonium chloride should be supplemented many a time, and quantity of supplement animonium chloride should be little at a time. 6.Validation of the experiment results of supplement of glucose and NH4CI The result obtained...