Characterization and Application of a Stationary Phase Promoter Library from Serratia marcescens .

Serratia marcescens has garnered increasing attention as a promising host for valuable compound production. However, the lack of an efficient gene regulation toolkit severely hampers its applications. Here, a library of stationary phase promoters was screened in S. marcescens HBA7 using RNA-seq and RT-qPCR, revealing a 43-fold regulatory range with the red fluorescent protein mKate2 as the reporter. The β-galactosidase was employed to demonstrate the universality in driving the expression of different proteins. The wide-ranging utility of these promoters in different hosts was demonstrated in Escherichia coli . Moreover, to assess their potential application, the strongest promoter, P2, was employed to express the swrW gene, resulting in a roughly 20-fold increase in serrawettin W1 production in S. marcescens HBQA7Δ swrW . In summary, this study successfully constructed a gradient-strength stationary phase promoter library, providing an effective toolkit for gene regulation and secondary metabolite production in diverse prokaryotes, including S. marcescens and E . coli .