Biodegradation of n-alkanes and polycyclic aromatic hydrocarbons using novel indigenous bacteria isolated from contaminated soils

Oil pollution is a major global environmental concern. Bioremediation is considered as a suitable approach for remediation of oil-contaminated environments. In this study, two crude oil-contaminated soils were collected to isolate and identify some native and active oil-degrading bacteria to be used in remediation of contaminated sites. Five isolates were selected according to “hole-plate diffusion method” and were grown in crude oil. They were cultured in a mineral salt medium in which crude oil was employed as the sole carbon source. Biochemical, morphological and genomic identifications demonstrated the bacteria species as Pseudomonas resinovorans, Plantibacter auratus, Bacillus subtilis, Staphylococcus pasteuri and Bacillus atrophaeus. These bacteria were able to degrade 86.0%, 61.3%, 81.1%, 55.0% and 76.2% of aliphatic compounds and 58.6%, 39.4%, 55.5%, 39.0% and 49.9% of aromatic hydrocarbons in a medium containing crude oil (1% v/v) over 21 days, respectively. The degradation rates of aromatic compounds from 14 to 21 days were higher than of aliphatic hydrocarbons. This rate was 28.4% by Bacillus subtilis, 30.9% by Bacillus atrophaeus, 27.2% by Staphylococcus pasteuri and 21.3% by Pseudomonas resinovorans. In Plantibacter auratus, this rate was 16.19% which is less than aliphatic hydrocarbons. To our knowledge, it seems this is the first time to report Pseudomonas resinovorans and Plantibacter auratus as crude oil degraders. Results of this study indicated that the isolated bacteria could have a high potential to be used in bioremediation of oil-contaminated environments.