Expanding the genetic toolkit: nitrogen-response promoters developed for Bacillus licheniformis

Promoters are crucial expression elements in synthetic biology, and Bacillus licheniformis serves as an excellent chassis cell for industrial production. However, compared with constitutive and carbon source-inducible promoters, nitrogen source-responsive promoters are lacking, restricting the application of B. licheniformis expression systems.

This study initially predicted nitrogen-responsive promoter elements through genomic analysis. Using enhanced green fluorescent protein (egfp) as a reporter gene, transcriptional initiation characteristics were evaluated.

Researchers found PglnR and Pgcv promoters could initiate transcription in response to sodium glutamate, with transcriptional intensities 200% and 100% higher than the control group at 36 h. Subsequently, these screened promoters were employed to mediate the expression of transglutaminase gene. In fed-batch fermentation using a 5-L glass fermentor, the recombinant strain achieved peak enzyme activity of 14.7 U/mL.

The work entitled “Mining, identification, and application of nitrogen-responsive promoters in Bacillus licheniformis” was published on Systems Microbiology and Biomanufacturing (published on September 03, 2025).