Antibacterial and anticancer activities of rhizobacterial lipopeptides against carcinogenic bacteria

Rhizosphere-derived lipopeptides, including surfactin, iturin, and fengycin from Bacillus spp., exhibit potent antibacterial and anticancer properties. This study evaluated the antibacterial activity, mechanism of action, anti-biofilm effects, and anticancer potential of these lipopeptides individually and in combination. The minimum inhibitory concentration (MIC) against pathogenic Gram-negative bacteria (Bacteroides fragilis, Escherichia coli, Fusobacterium nucleatum, Helicobacter pylori, Neisseria gonorrhoeae, Porphyromonas gingivalis, and Salmonella enterica) was determined using the broth dilution method. Among the single lipopeptides, fengycin demonstrated the strongest antibacterial effect, whereas the combination of all three lipopeptides exhibited the lowest MIC values, reducing bacterial growth by approximately 95% more than chloramphenicol. Mechanistically, lipopeptide treatments increased bacterial membrane permeability, with the three-lipopeptide mixture inducing 60% greater electrolyte leakage than chloramphenicol. Additionally, lipopeptides significantly reduced bacterial DNA content, with the three-lipopeptide combination leading to a 321% greater reduction than chloramphenicol. Biofilm formation was also markedly inhibited, particularly by fengycin and the lipopeptide mixtures. Furthermore, the anticancer activity of lipopeptides was assessed using the MTT assay against gastric, pancreatic, liver, colon, esophageal, and breast cancer cell lines. The three-lipopeptide mixture exhibited the highest cytotoxicity, with IC50 values approximately 82% lower than those of doxorubicin. These findings highlight the potential of rhizosphere lipopeptides as promising antibacterial and anticancer agents, warranting further investigation for therapeutic applications.