Effect of vegetable oils on the growth and spinosad biosynthetic potency of Saccharopolyspora spinosa

In order to investigate the influence of vegetable oils on the growth and spinosad biosynthetic potency of Saccharopolyspora spinosa and explore new methods to improve the yield of spinosad, six kinds of vegetable oils, including sunflower oil, peanut oil, soybean oil, sesame oil, olive oil and rapeseed oil were screened. To study their influence on the growth, the lipase activity and the spinosad synthetic potency of S.spinosa, different vegetable oils were added to the fermentation medium as partial carbon sources, respectively. In addition, the temporal transcriptional profiles of the lipase gene and some selected genes in the spinosad biosynthetic pathway were examined by RT-PCR. The results indicated that the effects of different vegetable oils on the growth of S. spinosa and the production of spinosad varied significantly, which were that rapeseed oil >olive oil >peanut oil >sesame oil >sunflower oil >soybean oil. The rapeseed oil was conducive to the induction of lipase expression, the delay of the decline phase of S. spinosa and the extension of the spinosad synthetic period. And the lipase activity, the biomass and the yield of spinosad were improved by 310.09%, 8.97% and 33.94%, respectively. The transcriptional intensity of lipase gene and spinosad synthetic genes were also promoted. Thus the rapeseed oil was the optimal candidate of auxiliary carbon sources among the selected vegetable oils.