Pseudomonas aeruginosa and Pseudomonas putida, as Grampositive and Bacillus subtilis and Bacillus licheniformis as Gramnegative strains were used as biological agents in biodegradation process of model mixture of hydrocarbons alone. Furthermore in the presence of the synthetic emulsifiers of polyoxyethylenated alcohol and alkylglucoside derivatives, natural emulsifier of rhamnolipid derivatives and anionic surfactants were used.