Characterization of Microorganisms Isolated from Petroleum Hydrocarbon Polluted Soil

Abstract

Bioremediation has received a great deal of attention, and bacteria isolated from polluted soil can be usedin that process. In this study, we performed an evaluation of the physiological groups of microorganisms fromsoil contaminated with petroleum. Bacterial strains were isolated from contaminated soil using the selectiveenrichment technique. Minimal Salt Media was used for serial dilutions to determine viable cell count. Thenumber of total viable cells and different types of microorganisms in the original sample was determined by serialdilution, agar plating procedure using selective media. The plates were incubated at 300C for 24-72 hours. Distinctcolonies growing on each plate were selected, and stored at freezing temperatures. The bacterial colonies werethen identified by Gram staining and biochemical tests. Following our research, it was observed that although thetotal microbial load of soil is relatively close in value, there are differences regarding the physiological group ofmicroorganisms. In the oil contaminated soil sample the largest group of microorganisms was the nitrous nitrifyingbacteria followed by nitrate bacteria. All bacterial strains that were isolated from soil samples contaminated withhydrocarbons but also the Pseudomonas putida and Bacillus subtillis strains can use diesel fuel as a food source.With the increase of diesel fuel concentration from culture medium, the majority of the bacterial strains that wereused in our experiments showed an increased value of absorbance. This fact suggests that these strains can be usedin bioremediation processes.