Structural characterization of biosurfactant produced by marine bacterium Pseudomonas fragi strain F1 (isolated from Persian Gulf) and evaluation of antimicrobial and antibiofilm activity

Abstract

Abstract The marine environment is a rich source of bioactive compounds, including biosurfactant-producing bacteria that exhibit unique characteristics and functionalities. In this study, we focused on glycolipid biosurfactants produced bacteria in a commensal relationship with marine organisms. We isolated and characterized a biosurfactant-producing strain, Pseudomonas fragi strain F1, which displayed high hemolytic activity (27mm), oil spreading ability (4mm), emulsification index (40%), and decreasing surface tension (31.3 mN/m). Fourier transform infrared (FT-IR) analysis revealed the glycolipid nature of the produced biosurfactant. Elemental analysis using CHNS and Energy Dispersive Spectroscopy (EDS) confirmed the presence of carbon, hydrogen, nitrogen, sulfur, chlorine, potassium, oxygen, and some other elements in the biosurfactant. The critical micelle concentration (CMC) of the biosurfactant was measured at 350 mg.L− 1, indicating its high efficiency. Furthermore, the biosurfactant demonstrated significant antimicrobial activity against Gram-positive and Gram-negative bacteria (the largest obtained ZOI was associated to P. aeruginosa with 27 mm), making it a potential alternative to synthetic drugs. The biosurfactant also exhibited substantial inhibition of biofilm formation and disruption, as well as enzymatic activity reduction in treated bacteria. Moreover, the mixture of biosurfactant and F1 bacterium enhanced the degradation of crude oil (86%), indicating its potential for environmental remediation. These findings highlight the importance of exploring commensal biosurfactant-producing strains in marine environments for hydrocarbon degradation, combating antibiotic resistance, and disrupting microbial biofilms.