Production and properties of biosurfactants from a newly isolated Pseudomonas fluorescens HW-6 growing on hexadecane.

The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l(-1)) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/ water interface by 35 mN m(-1) and possessed a low critical micelle concentration value of 20 mg l(-1), which indicated high surface activity. They efficiently emulsified aromatic hydrocarbons, kerosene, n-paraffins and mineral oils. Biosurfactant production contributed to a significant increase in cell hydrophobicity correlated with an increased growth of the strain on hexadecane. The results suggested that the newly isolated strain of Ps. fluorescens and produced glycolipid biosurfactants with effective surface and emulsifying properties are very promising and could find application for bioremediation of hydrocarbon-polluted sites.