Abstract：Abstract Saccharopolyspora spinosa (S. spinosa) is an important industrial microorganism known for spinosad production, which is a kind of biological insecticides with high efficiency, broad spectrum and low toxicity. At present, the yield of spinosad is low for industrial production in China. In order to improve the yield of spinosad, it is necessary to gain insight into the regulatory mechanisms and networks of spinosad biosynthesis in S. spinosa. Studies have shown that quorum sensing affects morphological differentiation and/or secondary metabolism in microorganism through cascade regulation. However, no report on the quorum sensing regulation mechanism of S. spinosa has been published yet. Present bioassay found that fermentation broth extract of S. spinosa could induce γ-butyrolactone (GBL)/receptor indicator strain Streptomyces coelicolor M145 to produce pigment, and the spinosad yield increased by 22.6% through adding water extract of its fermentation broth, which indicates that there is GBL/receptor cascade regulation of quorum sensing in S. spinosa. Bioinformatics analysis showed that S. spinosa had one GBL receptor homologous protein SsbR(Saccharopolyspora spinosa γ-butyrolactone receptor) and 3 central transcription regulators homologous proteins SstA1, SstA2, SstA3 (Saccharopolyspora spinosa central transcription activator). Real-time quantitative PCR (qRT-PCR) was used to detect the expression of key homologous genes related to cascade regulation. The expression levels of ssbR and sstAs during the fermentation conformed to model that the expression of sstAs was repressed by SsbR. In addition, the expression levels of 3 target proteins homologous genes griR (grixazone regulator), sprA (serine protease A) and ssgA (sporulation of Streptomyces griseus A) in S. spinosa were the same as that of sstAs, which suggests that these 3 genes may be activated by SstAs. This study provides a reference for the further research of the quorum sensing regulation mechanism of S. spinosa.
