Understanding the Antifungal and Antibiofilm Potential of a Naturally Occurring <i>Bacillus</i> Lipopeptide

Candida albicans has been recognized as a WHO-prioritized critical fungal pathogen that requires urgent attention, as it can potentially cause life-threatening infections. Antifungal agents may become ineffective in the future due to the rapid emergence of antifungal resistance, potentially rendering them unable to treat biofilm-associated infections. The present investigation employs various in vitro techniques, such as antifungal susceptibility, in vitro pharmacodynamics, advanced electron microscopy, zeta potential assessment, and rhodamine 6G efflux assay, to evaluate the anti-Candida and anti-biofilm activities of the Bacillus-derived lipopeptide against planktonic cells and mature fungal biofilms. Time-kill assays indicated a significant reduction in CFUs, while scanning and transmission electron microscopy revealed pronounced ultrastructural damage and surface deformation in lipopeptide-treated cells. A significant reduction in mature Candida biofilms determined by resazurin and safranin-based assays was observed at different concentrations, comparable to amphotericin B. In both lipopeptide- and amphotericin B-treated mature biofilms, the entangled network of massive hyphae was absent compared to the controls. COMSTAT analysis indicated a marked reduction in lipopeptide-treated biofilm biomass, and confocal microscopy results corroborated these observations.