Background: Biosurfactants (BSs) are amphipathic, surface active molecules produced by microorganisms and can reduce the surface tension and interfacial tension. The present study emphasizes the isolation and structural characterization of the BS produced by Pseudomonas otitidis P4.Results: An efficient BS producing bacterial strain isolated from the unexplored coal mining site of Chirimiri, India was identified as P. otitidis P4 based on morphological, biochemical and 16S rRNA gene sequence analysis. The surface tension of the culture medium was reduced from 71.18 to 33.4 mN/m. The surface tension and emulsification activity of the BS remained stable over a wide range of temperature, pH and salt concentrations indicating its scope of application in bioremediation, food, cosmetics, and pharmaceutical industries. Structural attributes of BS were determined by biochemical tests, thin layer chromatography (TLC), Fourier transform infrared (FTIR) and nuclear magnetic resonance ( 1 H NMR) spectroscopy analyses, which confirmed the glycolipid nature of BS. Lipid and sugar fractions were the main constituents of the extracted BS. Thermogravimetric (TG) and Differential scanning calorimetry (DSC) analyses showed the thermostable nature of BS. As determined from TGA graph, the degradation temperature of biosurfactant was found to be 280 °C while complete weight loss was observed after 450 °C. Conclusion:The BS isolated from P. otitidis P4 was identified as glycolipid and showed high emulsification activity and stability in a wide range of temperature, pH and salinity which makes it suitable for various industrial and environmental applications.

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