Antibiofilm Activity of Lactobacillus acidophilus Derived Bacteriocins against Biofilm-Forming Clinical Pathogens

Abstract

Biofilm-producing bacteria infections have been shown to be a great challenge in the clinic because of the high tolerance of the biofilm to antibiotics and host immune system, hence resulting in antimicrobial resistance. Consequently, natural antibiotics with both antibacterial and antibiofilm abilities are greatly needed. In this study, we investigated the antibacterial and antibiofilm activities of the crude bacteriocin produced by Lactobacillus acidophilus against biofilm producing pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae. Bacteriocin were prepared from overnight cultures using procedures that involved centrifugation, neutralization, catalase treatment, and membrane filtration of cultures. The activities of bacteriocin were determined using activity units (AU/mL) with Lactobacillus plantarum as an indicator strain. Antibacterial activity was performed using agar well diffusion method and minimum inhibitory concentration (MIC), while antibiofilm activity was done using crystal violet microtiter plate. The bacteriocin has the ability to inhibit all the tested pathogens with inhibition zones of 15.0 ± 0.9 to 22.0 ± 1.2 mm. The bacteriocin has the highest activity against S. aureus while K. pneumoniae was found to be the least susceptible. The MIC values for the strains tested ranged from 25 to 100 AU/mL. Also, the bacteriocin was able to inhibit biofilm formation by 81.5 ± 2.1%, 72.3 ± 1.8%, 68.4 ± 2.0%, and 63.7 ± 1.9% against S. aureus, P. aeruginosa, E. coli, and K. pneumoniae, respectively (P < 0.05). Antibiofilm activity was found to increase dose-dependently with its maximum at 100 AU/mL.