The statistical optimization and investigating anti-biofilm effect of the surfactin produced from Bacillus paramycoides

Abstract

Abstract Background Biosurfactants produced from bacterial strains are widely used due to their high efficacy and safety as well as their wide range of applications in the medical, pharmaceutical, and petroleum fields. This study aims to present biosurfactant production from a locally isolated Bacillus paramycoides strain, then characterize and optimize its activity and assess its ability as an anti-biofilm agent against different biofilm-forming strains. Results From 231 soil samples, a 16S rRNA identified Bacillus paramycoides strain was isolated and considered as the highest bacterial strain producing biosurfactants. The biosurfactant produced from the chosen B. paramycoides strain was determined using mass spectrometry as surfactin; this biosurfactant exhibited a critical micellar concentration of 200 µg/mL. The Box Behnken Design (BBD) design was used to screen the significant factors of the medium’s components. This optimization model demonstrated a 1.6-fold increase in surfactin activity compared to the non-optimized conditions in the fermentation medium. The surfactin stability was assessed with a wide range of temperatures, pH, and salinity to show that surfactin stability was maintained at 20 to 35 °C, pH ranges from 5 to 7, and at salinity of 2 to 4%. The anti-biofilm activity of the tested surfactin was performed to find that P.aeruginosa has the highest response to the tested surfactin, as the biofilm formation was inhibited up to 64% in a concentration of 250 µg/mL. At the same time, S. aureus showed a lower response to the tested surfactin, as the biofilm formation was inhibited up to only 13% in a concentration of 250 µg/mL of surfactin. Conclusion This study concluded that surfactin showed its maximum values at low temperatures and salinity and slightly acidic pH values. Surfactin at lower concentrations also exhibited strong antibiofilm activity against P.aeruginosa strains.