Optimization of spinosad production by Saccharopolysosa spinosa YJY-12 and its application in controlling Eggplant Thrips.

In this study, a new isolated strain YJY-12 with high yield of spinosad was isolated and its fermentation conditions for spinosad production was optimized. It was preliminary identified by morphological and molecular biology analysis to be S. spinosa YJY-12, and it demonstrated stable high-yield trait, with a variation of less than 5% in fermentation levels across five generations. Subsequently, its fermentation condition for producing spinosad was optimized in shake flask experiments. The process involved single-factor tests, Plackett–Burman (PB) experiments, steepest ascent experiments, and central composite design (CCD) methodology. After optimization, the spinosad fermentation level by strain YJY-12 reached up to 4.38 g/L. The fermentation process was further scaled up to a 30-L fermentor by fed-batch fermentation, achieving a spinosad fermentation level of 6.22 ± 0.12 g/L after 16-day. Finally, the efficacy of spinosad in controlling Eggplant Thrips was investigated and the technical spinosad produced by strain YJY-12 exhibited superior efficacy of thrips control. Overall, this study provided a methodological foundation for enhancing spinosad fermentation efficiency and offers guidance for future spinosad fermentation optimization research.