AimsThis work aimed to study, isolate, characterize and stabilize the biosurfactant isolated from actinomycetes found in petroleum contaminated soil. Methods and ResultsOptimized production of the biosurfactant from Streptomyces griseoplanus NRRL-ISP5009, SM1 was obtained on day 6 at 30 degrees C, pH 7, 150revmin(-1), in glycerol yeast extract broth medium supplemented with cellulose, yeast extract and 1% NaCl. The stability of the biosurfactant produced was studied at different temperatures, pH and different concentrations of NaCl. The produced biosurfactant was extracted and purified. ConclusionStreptomyces griseoplanus NRRL-ISP5009, SM1 isolated from oil contaminated soil produced a biosurfactant exhibiting emulsification activity. The produced biosurfactant is a mixture of carbohydrate, lipid and protein. It has promising characteristics, including a higher stability at alkaline pH than at acidic pH, a salinity of 1-3% and stable in the temperature range from 0 and 100 degrees C. Also, the potential antimicrobial activity of the purified biosurfactant was recorded. Significance and Impact of the StudyThe research was focused on the isolation of a novel source of biosurfactants that have great importance in the manufacture of food, detergent, pharmaceutical and cosmetics.