Abstract
Due to human progress in various areas, the demand for oil and its products has increased. This leads to an increase in environmental contamination and serious problems worldwide. A wide range of microorganisms produce biosurfactants which have the ability to degrade oil. The aim of this study was to isolate biosurfactant-producing bacteria from wastewater contaminated with oil and oil sludge in Asemari and Bangestan, Iran. To evaluate biosurfactant activity, bacterial strains were isolated from samples and characterized by assays including hemolytic activity, oil spreading, emulsification activity, and surface tension. The isolates with the highest biosurfactant production activity were identified by morphological, biochemical, and molecular methods. The samples yielded 23 isolates, of which 15 had hemolytic properties. Among them three isolates with the highest biosurfactant activity were selected based on oil spreading test, emulsification activity, and surface tension. The isolates were identified as Pseudomonas mendocina, Pseudomonas alcaliphila, and Planococcus halotolerans. The oil degradation of the isolates was assessed. The breakdown of long chain hydrocarbons in oil-containing culture medium was caused by all three isolates, as revealed by GC chromatography. The present findings indicate that certain microorganisms present in oil-contaminated regions are capable of producing biosurfactants. Further research is needed to isolate and identify strains with the highest ability to produce biosurfactants for industrial purposes.