Effects of Glucose and Phosphate on Spinosad Fermentation by Saccharopolyspora spinosa1

The effects of glucose and inorganic phosphate on mycelium growth and spinosad production with Saccharopolyspora spinosa were studied. The results showed that the increase of glucose concentration from 18.6g·L−1 to 58.8g·L−1 could promote the mycelium growth and spinosad production. And when the glucose concentration increased from 58.8g·L−1 to 79.6g·L−1, no obvious change was detected but a slight drop in spinosad production was observed, whereas, when the glucose concentration increased from 79.6g·L−1 to 115.3g·L−1, substantial decrease in both mycelium growth and spinosad production occurred. The increase of phosphate concentration from 3.68mmol·L−1 to 29.41mmol·L−1 rendered corresponding increase in mycelium growth and spinosad production. When phosphate concentration increased from 29.41mmol·L−1 to 44.12mmol·L−1, mycelium growth slightly increased and spinosad production dropped, while when phosphate concentration increased from 44.12mmol·L−1 to 57.62mmol·L−1, both mycelium growth and spinosad production decreased sharply. Conclusively, the optimal initial concentration of glucose and phosphate is 58.8g·L−1 and 29.41mmol·L−1, respectively. The spinosad fermentation in the production medium containing 58.8g·L−1 glucose and 29.41mmol·L−1 phosphate was scaled up in 5-L fermentation and the spinosad production reached 507mg·L−1, which was 28% higher than that in the flask fermentation.