In this study, among the 21 diesel-degrading bacteria that were isolated from an oil-polluted area in Fars (Iran), 6 bacterial strains were tested for their capability to metabolize and grow on diesel oil by degrading its hydrocarbons content. The biochemical characteristics and 16S rRNA sequence analysis of diesel-degrading bacteria showed that these strains were related to the genus Pseudomonas. Among the six isolates, five strains (L1, I2, D1, D2, and G1) were clustered with Pseudomonas aeruginosa, whereas only one strain (K3) was clustered with Pseudomonas fragi. Gas chromatographic (GC) analysis of the diesel oil that was remaining in the culture medium after 10 days of culture at 30°C showed that P. aeruginosa I2 presented the highest growth rate and diesel-oil degradation (88%) between all isolates. P. aeruginosa I2 also presented the best emulsification activity, but the best hydrophobicity was seen in P. aeruginosa G1. By applying these bacteria in bioremediation processes, diesel oil contamination in soil can be counteracted.

Kerosene is the colorless liquid and slightly heavier than gasoline thatspecific odor removes after evaporation. Soil and underground water source arecontaminated with different pollutants such as petroleum hydrocarbons. These pollutantshave various negative environmental effects on soil and surrounding environment. Theaim of this research is to understand the effect of kerosene pollution on two differentsoils. The two different collected soils include Industrial and Forest soil. Six microcosmswere designed. Indeed, each soil has three microcosms: unpolluted microcosm, pollutedmicrocosm, and polluted microcosm with nutrient (Nitrogen and Phosphor). Some factorswere assayed in each microcosm during 120 day of experiment. These factors includetotal heterotrophic bacteria, total kerosene degrading bacteria, dehydrogenase enzyme,and kerosene biodegradation. The results of this study show that the highest quantity ofheterotrophic bacteria is related to forest soil (6×109). The quantities of kerosenedegrading bacteria significantly were lower than heterotrophic bacteria in all soilmicrocosms. The quantity of kerosene degrading bacteria have decrement pattern until60th day of experiment, but, after this day, these bacteria have increment pattern. The bestdehydrogenase activity between different microcosms is related to polluted microcosmwith kerosene except for farmland soil. The highest biodegradation of kerosene in allstudied soil belongs to industrial microcosm (95%). Statistical analysis of the resultsshows that there is a significant correlation between MPN quantity of heterotrophicbacteria and other assayed factrs. Also, forest soil has significant difference with othersoils. It may be possible to propose appropriate strategies for bioremediation of differentstudied soil types using the results obtained in this research.