Abstract: The optimal extraction conditions of doramectin in fermentation broth of Streptomyces avermitilis were investigated by parallel experiments. Factors including distribution ratio of doramectin in fermentation broth (hyphae or supernatant), extractants, extraction times, storage time, pH and temperature on extraction results were investigated with one-factor experiments. Meanwhile, the optimal extraction times and extracting volume were optimized based on using ethyl acetate. The optimal extraction conditions of doramectin in fermentation broth of Streptomyces avermitilis were obtained as follows: the optimal extraction solvent was methanol, and doramectin in fermentation broth could be stored for at least 144 h within the conditions of pH from 3 to 13 and temperature from 20 to 80 ℃. Using ethyl acetate to extract doramectin, twice was the optimal extracting time, and the twice volume of ethyl acetate and concentrated extract was the best extraction proportion. Under the optimal extraction conditions, the concentration of doramectin and its extraction rate were 151.78 μg/mL and 98.00%, respectively.

Key words: doramectin, fermentation broth, extraction condition