Bioremediation of soils polluted by petroleum hydrocarbons by Pseudomonas putida

In order to clean up soils contaminated with hydrocarbons, the bioremediation activity of Pseudomonas putida was studied. Pseudomonas putida is a bacterium that can withstand the harshest environmental conditions. It is able to metabolize a wide range of petroleum hydrocarbons which is used as a source of carbon and energy. Given the potential of this microorganism, an experiment wasconducted on this strain. For the isolation of this microorganism, a sample ofsoil from the Vakinankaratra region in the urban commune of Antsirabe II, Madagascar was microbiologically analysed. The bacterial identification was based on a study of the morphological, physicochemical and sequential analysis of the 16S rDNA gene. The isolated strain was then inoculated into soil polluted by diesel engine oil from the garage at Universityof Saint Joseph Antsirabe, Madagascar. The kinetics ofbacterial growth showed that the biomass increased from 4.107 to 3.1013 CFU/g at the end of the experimentation. A growth rate of 0,32h-1 and a generation time of 2,16 hours were noted. The quantification of the residual hydrocarbons according to the EPA method (Environmental Protection Agency) 3540C have made it possible to deduce the capacity of degradation of the bacterial strain which is 0,2 mg of hydrocarbon per gram of soil per day. After 3 months of biological treatment, the concentration of the residual petroleum hydrocarbons had been reduced by 30%(from 18000 mg/kg to 5000 mg/kg). Thus, the ability of Pseudomonas putida to decontaminate polluted soils with hydrocarbons has been observed.