Correlation between pyocyanin production and hydrocarbonoclastic activity in nine strains of Pseudomonas aeruginosa

The more pyocyanin produced by the hydrocarbon degrading Pseudomonas aeruginosa strains, the more hydrocarbons would be assimilated and transformed. To evaluate this assumption,we asssed the potential use of nine wild types of pyocyanin-producing P. aeruginosain bioremediation. They exhibit concentrations of pyocyanin ranging from 0.08 to 28.68 μg/mL.Hydrocarbonoclastic activity in the presence of pyocyanin was determined by two protocols. First, ahigh correlation was found between the synthesis of pyocyanin and the emulsification index of lubricating oil. Second, two strains were tested for their ability to degrade anthracene and pyrene in soil by the concentration of pigment produced.Microcosms were filled with 250g of sterile sandy soil, supplemented with glycerin and then contaminated with a 20 mg/kg of mixture of the two compounds. The volume of the inoculum suspension (≈108 CFU/mL) was equivalent to 5% of the soil mass contained in the microcosms. Static incubation lasted 60 days at 25°C. A roughly 60-fold difference between the pigment concentrations produced by the two strains resulted in an increase of 65 and 45% in the pyrene and anthracene biodegradation, also indicating that the molecule served as a co-substrate of pyrene degradation.