LI Shi-Hang1, YE Rui-Fang1*, 吕He-Ping2 , MAO Quan-Gui2, DAI Wei2
2012, 43(11): 896-902.
Demethylchlortetracycline(1) was prepared from Streptomyces aureus. The components of the culture medium were optimized. Three important ingredients which influenced the potency obviously in fermentation medium were found by Plackett-Burman experiment through Minitab software and they were corn starch, soybean meal and CaCO3. The optimal concentrations of the three ingredients were determined by steepest ascent search and response surface optimization. The results revealed that the potency was 25% - 31% higher than the initial fermentation medium at corn starch of 110 g/L, soybean meal of 43 g/L and CaCO3 of 7 g/L. The experiments about changing C/N and adding amino acids indicated that the potency increase was possibly caused by many factors. After the analysis of the related organic acids and CoA carboxyl transferase, the results indicated that more extracellular oxaloacetic acid and malonic acid were accumulated in the optimized medium in the middle phase. Both of them entered into the cells at the end of fermentation and the demethylchlortetracycline was synthesized greatly. The results also indicated the trend of enzymatic specific activity was anastomotic with that of malonic acid and the potency.