Application of genetically engineered dioxygenase producing pseudomonas putida on decomposition of oil from spiked soil

Abstract

Background: It is well known that bioremediation or using microorganism enzymes plays an important role in decomposition and changing of oil pollutants and PAH compounds into nonhazardous or less-hazardous substances. The genetically manipulated bacteria like Pseudomonas sp. can enhancement the natural biodegradation activity of polycyclic aromatic hydrocarbons (PAHs) in polluted cities. Pseudomonas putida (P. putida) is a saprotrophic soil bacterium that is found throughout various environments such as soil and freshwater environments. Oil and petroleum industries are important exposure of PAHs in environment that strongly associated with the development of human cancers. Objectives: In the present work, P. putida was genetically manipulated for the biodegradation of oil in spiked soil and its activity was measured using the high-performance liquid chromatography (HPLC) method. Methods: The catechol 2,3-dioxygenase (C23O) encoded gene (nahH) was cloned into pUC18 for generating pUC18-nahH. This recombinant vector was transferred into P. putida, successfully, and both wild type and genetically modified P. putida were inoculated in spiked soil with oil for pilot plan preparation. Then, biodegradation activity of this bacterium on the elimination of phenanthrene and pyrene as an oil indicator in spiked soil were evaluated by the HPLC measurement technique. Results: The results showed the biodegradation of these PAH compounds in oil-spiked soil by genetically manipulated P. putida in both groups (containing autoclaved soil and dish containing natural soil) comparing to the inoculated group by wild type of P. putida were statistically significant (P < 0.05). Finally, confirmatory tests (catalase, oxidase, and PCR) were accomplished on isolated bacteria from spiked soil and were indicated that engineered P. putida was alive and functional by producing the C23O enzyme for biodegradation activity of oil. Conclusions: These findings demonstrated a degradable strain of P. putida that was generated in this study by genetic engineering can be useful to assess biodegradation of PAHs compounds in oil and petrochemical pollutions.