Efficient Autoinducible Expression of Recombinant Proteins via the DegSU Quorum Sensing System in a Robust .

DegSU quorum sensing (QS) system enables autoinducible expression of recombinant proteins in . However, insufficient promoter strength and a complex regulatory circuit limit its practical application. Here, the QS-responsive promoter P was modified by core region mutation, upstream truncation, and addition of activating binding sites, yielding P with a 118.3% increase in strength. A mathematical model was developed to accurately quantify the regulatory process from a comprehensive perspective. Guided by this model, the DegSU QS system was further optimized in a robust by knocking out competitive target genes and , operons and , introducing variants and 36, and increasing regulatory strength by 84.0%. A 52.5% increase in acetoin titer and a 65.9% increase in extracellular carboxypeptidase activity validated the industrial value of this study. Overall, this study addresses the limitations of the DegSU QS system in practical application and demonstrates its potential for high-level recombinant protein production.