Evaluation of the effects of polymyxin B and bacteriocin extracted from Lactobacillus plantarum on surface hydrophobicity, alginate production, motility, and biofilm formation in Pseudomonas aeruginosa

The indiscriminate use of antibiotics has led to the emergence of antibiotic-resistant bacterial strains, highlighting the need for alternative therapeutic strategies such as probiotics. This study aimed to investigate the inhibitory effects of bacteriocin derived from Lactobacillus plantarum and the antibiotic polymyxin B on biofilm formation and certain virulence factors of Pseudomonas aeruginosa.

In this experimental study, 30 clinical isolates of P. aeruginosa were obtained from various clinical samples. The isolates were identified using standard biochemical and microbiological assays. Bacteriocin was extracted from the L. plantarum strain MT.ZH293. The effects of bacteriocin and polymyxin B on biofilm formation, surface hydrophobicity, alginate production, and bacterial motility were assessed. The minimum inhibitory concentration (MIC) was determined using the microdilution method.

For polymyxin B, the MIC was 4 µg/mL in 13.33% of isolates and 8 µg/mL in 86.6% of isolates. Regarding bacteriocin, 20% of isolates showed an MIC of 125 µg/mL, while 80% exhibited an MIC of 250 µg/mL. Following treatment with polymyxin B, 46.6% of isolates formed strong biofilms, 46.6% moderate, and 6.6% weak biofilms. In contrast, treatment with bacteriocin resulted in 13.3% of isolates forming moderate biofilms and 86.6% forming weak biofilms. Bacteriocin was more effective than polymyxin B in inhibiting biofilm formation, reducing surface hydrophobicity, and suppressing alginate production. Additionally, bacteriocin exhibited greater inhibition of twitching motility (within the range of 40 to 60 mm), while both treatments enhanced swarming motility.

The bacteriocin derived from L. plantarum demonstrated greater efficacy than polymyxin B in inhibiting biofilm formation and associated virulence factors, such as surface hydrophobicity and alginate production in P. aeruginosa. Thus, this bacteriocin may serve as a promising alternative strategy for managing antibiotic-resistant bacterial infections.