Novel polygalacturonase PG-BG31 prevents biofilm formation and increases antibiotic efficacy against catheter-associated Escherichia coli

Escherichia coli is a leading cause of urinary tract infections, which are particularly problematic in catheterized patients due to the formation of biofilms that are resistant to standard treatments. Here we investigated a novel polygalacturonase (PG-BG31) from Pedobacter sp. BG31 and its anti-biofilm properties against E. coli isolates originating from the urine of UTI patients. The enzyme was heterologously expressed and biochemically characterized using polygalacturonic acid as substrate. The enzyme showed strong biofilm inhibition with BIC50 values between 2 and 5 µg/mL, which varied depending on the E. coli strain. It outperformed enzymes commonly used in E. coli biofilm studies, including proteinase K, DNase and cellulase. When used as a pretreatment, it significantly improved the efficacy of ciprofloxacin and trimethoprim by reducing biofilm formation by 4 log (99.99 %) at lower antibiotic concentrations. Polygalacturonase PG-BG31 works optimally at temperatures of 25 °C - 42 °C and a slightly acidic pH value (pH 5.0 – 6.0), which corresponds to the environment in urine. In addition, the enzyme showed no toxicity to cells in culture or C. elegans. These results suggest that polygalacturonase has the potential for the development of anti-biofilm strategies for catheter-related urinary tract infections.