Anti-Biofilm Properties of Cell-Free Supernatant from <i>Bacillus velezensis</i> EA73 by In Vitro Study with <i>Staphylococcus aureus</i>
2025
Ziyao Tang | Muhammad Yousif | Samuel Kumi Okyere | Fei Liao | Siqi Peng | Lin Cheng | Feng Yang | Yuting Wang | Yanchun Hu
Endophytes are a potential source of novel bioactive antimicrobial compounds. A previous study showed that <i>Bacillus velezensis</i> EA73, an endophytic bacterium, has promising antibacterial activity against <i>Staphylococcus aureus</i>; however, the mechanisms associated with its activity have still not been investigated. Therefore, this study was conducted to investigate the molecular mechanisms involved in the anti-biofilm activity of a cell-free supernatant (CFS) of <i>B. velezensis</i> EA73 against <i>S. aureus</i>. In this experiment, the biofilm-eliminating effects of a CFS of <i>B. velezensis</i> EA73 against <i>S. aureus</i> were examined in vitro. RT-qPCR was used to detect the changes in genes related to biofilm formation, whereas network pharmacology was used to predict the key targets and pathways of a cell-free supernatant of <i>B. velezensis</i> EA73 against <i>S. aureus</i>-mediated diseases. The minimum biofilm eradication concentration (MBEC) of the EA73 CFS against <i>S. aureus</i> was 1.28 × 10<sup>−3</sup> g/mL. In addition, we observed that the EA73 CFS reduced bacterial adhesion and decreased extracellular proteins, polysaccharides, and the eDNA content in the biofilm and decreased the expression of biofilm-associated genes, such as <i>icaA</i> and <i>sarA</i>. The EA73 CFS had a significant effect on <i>S. aureus</i> biofilm eradication and hence can serve as a promising antibacterial reagent.
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