Isolation and Characterization of Biosurfactant-Producing Enterobacter hormaechei subsp. hoffmannii MK-DU2 with...

Oil pollution has led to the growth of microbial communities producing biosurfactants that increase the bioavailability of petroleum hydrocarbons. This study aimed to isolate and characterize a new biosurfactant-producing strain as an alternative to toxic chemical surfactants. Soil samples were screened for biosurfactant-producing isolates using oil spread, drop collapse, and hemolysis tests. A biosurfactant extract was obtained from the selected isolate investigated for its emulsification properties and ability to enhance crude oil biodegradation. Characterization of the extract was performed using thin-layer chromatography, Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H-NMR), and thermogravimetric analysis (TGA). The crude biosurfactant extract reduced surface tension to 44.4 mN/m and enhanced microbial crude oil biodegradation, achieving 99.23% removal efficiency. FTIR analysis revealed the presence of OH-, N-H, CH, CH₂, CH₃, and ester groups, while ¹H-NMR identified aliphatic chains, fatty acids, amino groups, and sugar moieties. The crude biosurfactant extract demonstrated significant emulsification activity at acidic pH and maintained stability in the presence of NaCl and KCl. Chemical characterization suggested the presence of both glycolipid and protein components in the extract. The biosurfactant-producing isolate, coded MK-DU2, showed 99.45% similarity to Enterobacter hormaechei subsp. hoffmanni based on 16S rRNA gene sequencing. These findings highlight the potential of this biosurfactant extract for various environmental and industrial applications.