Exploration of the Native Sucrose Operon Enables the Development of an Inducible T7 Expression System in Paenibacillus polymyxa .

The use of Paenibacillus polymyxa as an industrial producer is limited by the lack of suitable synthetic biology tools. In this study, we identified a native sucrose operon in P. polymyxa . Its structural and functional relationship analysis revealed the presence of multiple regulatory elements, including four ScrR-binding sites and a catabolite-responsive element (CRE). In P. polymyxa , we established a cascade T7 expression system involving an integrated T7 RNA polymerase ( T7P ) regulated by the sucrose operon and a T7 promoter. It enables controllable gene expression by sucrose and regulatory elements, and a 5-fold increase in expression efficiency compared with the original sucrose operon was achieved. Further deletion of SacB in P. polymyxa resulted in a 38.95% increase in the level of thermophilic lipase (TrLip) production using the cascade T7 induction system. The results highlight the effectiveness of sucrose regulation as a novel synthetic biology tool, which facilitates exploring gene circuits and enables their dynamic regulation.