Bioremediation of Sterile Agricultural Soils Polluted with Crude Petroleum by Application of the Soil Bacterium, Pseudomonas putida, with Inorganic Nutrient Supplementations

The effects of bioremediation program of sterile agricultural soils contaminated with crude petroleum were determined with a view to developing a suitable technique for rehabilitation of similar environments upon pollution by oil spillage. Sterile soils inoculated with the soil bacterium, Pseudomonas putida (PP), with inorganic nutrients monitoring and supplementation constituted the experimental set-ups (ESU). The control set-ups (CSU) contained all the materials present in ESU except that they were not inoculated with PP. In ESU at week 9, the oil pollutant was completely biodegraded, and the inorganic nutrient ions, particularly PO₄ ⁻³ and NO₃ ⁻¹, were significantly utilized. In contrast, there were no significant changes in the concentrations of oil and inorganic nutrients in CSU. Also, the percentage germination and growth profiles of cress seeds (Lepidium sp.) planted as evidence of the recovery of the oil-impacted soils were poor in CSU (27.5%) with pronounced abnormal morphology when compared with the results obtained for ESU (98.8%). Inoculation of PP with addition of appropriate inorganic nutrients may be a suitable method for a rapid rehabilitation of agricultural land upon pollution with crude petroleum. Received: 28 June 2000 / Accepted: 5 September 2000