Avermectin Production Process

The techniques of fermentation and extraction of avermectins production by Streptomyces avermitilis 1107VII-21-55 were studied; and the factors affecting the biosynthesis of avermectins were explored in this paper.Firstly, The seed culture media and the fermentation culture media were screened, which were used in the secondary fermentation of avermectins. Results showed that the titer and the proportion of avermectin B1 in the culture increased by more than 20% and 5% respectively by using the improved secondary fermentation medium compared with the control medium. When the fermentation titers were measured, it was found that the highest avermectin B1 concentration in the culture was obtained when 30ml culture was growing in 250ml shaking flask; when the total avermectin B1 productivity (fermentation index) was measured, it showed that the highest productivity was acquired when 60ml culture was fermented in 250ml shaking flask. The titer of avermectin B1 increased by 9% when the temperature of secondary fermentation decreased to 26 at 72h. The titer of avermectin B1 increased by 25% through supplementing appropriate amount of glucose and yeast powder.Based on above screened secondary fermentation conditions, the conditions of trinary fermentation were studied afterwards. The results indicated that the titer and total productivity of avermectin B1 in the trinary fermentation increased by 10% and 20% respectively compared with the secondary fermentation under the same conditions.The relationship between avermectins biosynthesis and the concentration of reductive sugar in the culture and the concentration of ATP within the mycelium cells was primarily explored with the same strain. The results showed that the titer of avermectin B1 was affected by above conditions.The extraction and purification experiments showed that when the content of water in the filtered mycelium was decreased to 56.9-64.5% by drying the mycelium; and the mycelium was extracted twice with 88% and 75% alcohol respectively; as well as avermectin B1 was crystallized after the solvent phase containing avermectins B1 being condensed to 80% of the initial volume by decompression evaporation, the total yield of B1 recovered increased by over 6.0%. This new techniques improved the quality of avermectins B1 products (with a higher product quality than national criterion). The improved processes of extraction and purification decreased the consumption of alcohol obviously, and deleted the use of acetone and resin totally. As a final result, this new techniques reduced the cost of avermectins B1 production greatly.