The efficacy of lyticase and β-glucosidase enzymes on biofilm degradation of Pseudomonas aeruginosa strains with different gene profiles

Abstract

Background: Pseudomonas aeruginosa is a nosocomial pathogen that causes severe infections in immunocompromised patients. Biofilm plays a significant role in the resistance of this bacterium and complicates the treatment of its infections. In this study, the effect of lyticase and β-glucosidase enzymes on the degradation of biofilms of P. aeruginosa strains isolated from cystic fibrosis and burn wound infections were assessed. Moreover, the decrease of ceftazidime minimum biofilm eliminating concentrations (MBEC) after enzymatic treatment was evaluated.

Results: This study demonstrated the effectiveness of both enzymes in degrading the biofilms of P. aeruginosa. In contrast to the lyticase enzyme, β-glucosidase reduced the ceftazidime MBECs significantly (P < 0.05). Both enzymes had no cytotoxic effect on the A-549 human lung carcinoma epithelial cell lines and A-431 human epidermoid carcinoma cell lines.

Conclusion: Considering the characteristics of the β-glucosidase enzyme, which includes the notable degradation of P. aeruginosa biofilms and a significant decrease in the ceftazidime MBECs and non-toxicity for eukaryotic cells, this enzyme can be a promising therapeutic candidate for degradation of biofilms in burn wound patients, but further studies are needed.

Keywords: Biofilm; Lyticase; Pseudomonas aeruginosa; β-Glucosidase.

Fig. 1

The effects of serial dilutions of (1) enzyme β-glucosidase [0.025 (a), 0.05 (b), 0.1 (c), 0.2 (d), and 0.4 (e) units mL^− 1] and (2) enzyme lyticase [1.25 (a), 2.5 (b), 5 (c), 10 (d), and 25 (e) units mL^− 1] on biofilms of P. aeruginosa strain BR1 that were evaluated by CV assay. The experiment was done once in triplicates. Error bars represent standard deviation (SD). Asterisks indicate the statistically significant difference with control (no enzyme treatment) (*P < 0.05)

Fig. 2

The effects of selected concentrations of enzymes (a) lyticase (2.5 units mL^− 1) and (b) β-glucosidase (0.05 units mL^− 1) against biofilm embedded P. aeruginosa strains with different gene profiles that were determined by colony counting technique. Error bars represent standard deviation (SD). Asterisks indicate the statistically significant difference before and after enzyme treatment (*P < 0.05)

Fig. 3

The effects of selected concentrations of enzymes lyticase (2.5 units mL^− 1) and β-glucosidase (0.05 units mL^− 1) against biofilm embedded P. aeruginosa strains with different gene profiles: a strain BR1, b strain BR7, c strain BR3, d strain BR8, and e strain CF3

Fig. 4

The scanning electron microscopy (SEM) images of P. aeruginosa biofilms (strain BR3). a Untreated control biofilm. b After 1 h treatment with enzyme β-glucosidase (0.05 units mL^− 1) (6000x magnification)

Fig. 5

Influence of the most effective concentration of enzymes lyticase (2.5 units mL^− 1) and β-glucosidase (0.05 units mL^− 1) on the viability of the A-549 human lung carcinoma epithelial cell lines and A-431 human epidermoid carcinoma cell lines after 24 h incubation. The experiment was done two times in duplicates. Error bars represent standard deviation (SD). The ns represent non-significant difference compared with control (no enzyme treatment) (P > 0.05)