Application of Bacillus Subtilis Antimicrobial Peptides to Control Pseudomonas Aeruginosa in Water Systems

Abstract

Pseudomonas aeruginosa is an opportunistic waterborne pathogen that has pronounced ecological and public health significance due to its ability to survive, risks biofilm formation when exposed to many therapeutic agents or natural resistance mechanisms and disinfectants. The increasing prevalence of antimicrobial resistance (AMR) in P. aeruginosa strains present in water systems has led to increased interest in technologically sustainable approaches especially those derived from biological sources but there is still limited understanding of their full potential as effective antimicrobial agents. The present is to evaluate and characterize the antimicrobial peptides of Bacillus subtilis that have specifically antibacterial activity against P. aeruginosa under simulated conditions of the water system in which both organisms are grown together. MethodologyA laboratory-controlled, randomized experimental study was conducted in the time period from summer 2024 to late autumn/early winter 2025. The negative control, positive control and treatment (crude and partially purified antimicrobial peptide extracts) groups were assigned randomly to P. aeruginosa ATCC 27853 inoculated sterile water. Antimicrobial activity was measured (viable bacterial count determination, agar well diffusion assay, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)). Treatment with antimicrobial peptides derived from B. subtilis reduced bacterial growth compared to untreated controls (p < 0.001). Results: The viable bacterial count was decreased by decreasing from 8.74 × 10⁵ CFU/mL in positive control to 3.42 × 10⁵ CFU/mL after crude peptide treatment, and again down to 1.18 × 10⁵ CFU/mL with the partially purified peptide treatment. Concurrently, the inhibition zone diameters increased significantly from 14.82 mm (crude extract) to 22.46 mm at partial purified peptides level, with respective MIC and MBC values in prepared purifications at lower levels presenting higher antibacterial potency. These results demonstrate that the water-soluble antimicrobial peptides of B. subtilis have strong inhibitory and bactericidal effects on P. aeruginosa with improved activity after partial purification, which support microbial product safety while also diminishing occurrence of resistant bacterial contaminants in water systems.

Keywords:

Pseudomonas aeruginosa ATCC 27853, Bacillus subtilis, antimicrobial peptides

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