Genomic and transcriptomic analysis of yield enhancement mechanism of lipopeptide iturin W by tryptone supplementation

In our previous studies, a novel lipopeptide, iturin W, exhibiting high antifungal activity, was discovered from <i>Bacillus</i> sp. wsm-1. To enhance its production, the effects of different carbon and nitrogen sources were detected, and only supplementation of tryptone significantly increased the yield of iturin W. In this study, the biosynthetic gene cluster of iturin W was identified through antiSMASH analysis of the <i>Bacillus</i> sp. wsm-1 genome, followed by gene knockout validation. The cluster comprises four open reading frames: <i>ituW-D</i>, <i>ituW-A</i>, <i>ituW-B</i>, and <i>ituW-C</i>. To elucidate the enhancement mechanism of iturin W production by tryptone supplementation, transcriptomic analysis was conducted. The results revealed that tryptone supplementation significantly upregulated the gene cluster responsible for iturin W biosynthesis, along with genes associated with the TCA cycle, ribosome function, pyruvate metabolism, fatty acid metabolism, and amino acid metabolism. Additionally, the quorum sensing system Rap-Phr and several key genes were closely linked to iturin W biosynthesis. Notably, the overexpression of BslA and cytochrome P450 gene together resulted in a more than threefold increase in iturin W production. Overall, this study not only provides insights into the yield enhancement mechanism of iturin W in response to tryptone supplementation but also identifies key enzymes and potential regulators involved in its biosynthesis, providing the foundation for the yield improvement of lipopeptide in the future.IMPORTANCELipopeptides exhibit a variety of biological activities and hold promising potential for various applications, but their practical use is largely limited by low yields. Medium optimization is a fundamental approach to enhance the yield of lipopeptide, and numerous studies have demonstrated that optimizing the medium can increase lipopeptide production to varying degrees. However, the underlying mechanisms driving these improvements have seldom been explored. In this study, the yield enhancement mechanism of iturin W by supplementation of tryptone has been investigated by transcriptomic analysis. The result not only elucidated the detailed pathway underlying iturin W production improvement but also discovered key enzymes and potential regulators involved in its biosynthesis. Overexpression of these genes significantly increased iturin W production. Collectively, our findings provide a valuable foundation for improving lipopeptide yields in the future.