Screening of quorum Sensing-Dependent strong promoters in Pseudomonas bijieensis 2P24 for metabolic optimization and Recombinant protein production.

Pseudomonas bijieensis 2P24, a bacterium isolated from the wheat rhizosphere, is known for producing secondary metabolites such as 2,4-diacetylphloroglucinol (2,4-DAPG), which exhibits strong inhibitory effects against soil-borne pathogens. The genome of P. bijieensis 2P24 also harbors the mupirocin biosynthetic gene cluster, underscoring its metabolic versatility and potential applications in pharmaceuticals. Within the mupirocin biosynthetic gene cluster, a luxI/luxR-type quorum-sensing system (MupI/MupR) regulates secondary metabolites production, linking quorum sensing to metabolic processes. Owing to its cost-effective growth conditions, P. bijieensis 2P24 has emerged as a promising candidate for microbial chassis and recombinant protein expression system. In this study, six strong promoters were identified using RNA-seq and ChIP-seq analyses of the quorum-sensing transcriptional regulator MupR, combined with an enhanced green fluorescent protein reporter system. These promoters were evaluated in the autologous 2,4-DAPG biosynthetic pathway and β-galactosidase expression in P. bijieensis 2P24. The quorum-sensing-dependent promoters significantly enhanced 2,4-DAPG production, while all six promoters demonstrated robust β-galactosidase activity with consistent performance. These findings highlight the potential of endogenous strong promoters for optimizing metabolic pathways and recombinant protein production, especially under quorum-sensing regulation. This study establishes P. bijieensis 2P24 as an effective platform for applications in agriculture, pharmaceuticals, and biotechnology.