Analysis of the antibacterial mechanism of Levan against Escherichia coli using differential gene expression analysis...

Levan, a fructose-based polysaccharide, has been widely reported to exhibit broad-spectrum antibacterial activity, highlighting its potential for biomedical applications. While its antimicrobial efficacy has been demonstrated, the global bacterial transcriptional responses associated with levan exposure remain insufficiently characterized. In this study, we investigated the cellular and transcriptional responses of Escherichia coli to levan treatment using differential gene expression (DGE) analysis and transmission electron microscopy (TEM). TEM observations suggested that levan exposure is associated with osmotic stress, as evidenced by cell shrinkage, leakage of intracellular components, and growth inhibition. Transcriptomic analysis indicated alterations in multiple pathways, including a shift toward anaerobic metabolism, activation of fermentation-related processes that may contribute to acidic stress, and reduced expression of genes involved in cysteine and sulfate uptake. Additionally, levan treatment was associated with decreased expression of genes linked to chromosome segregation, cell division, biofilm formation, adhesion, quorum sensing, and motility. Collectively, these findings provide putative transcriptomic insights into how levan may influence bacterial physiology and offer a foundation for future mechanistic and validation studies.