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Aim: To assess the bioremediation potential of Pseudomonas aeruginosa and Bacillus megaterium on oil spill dispersant polluted terrestrial soil.
Study Design: The study employs experimental design, statistical analysis of data and interpretation.
Place and Duration of the Study: Polluted Terrestrial Soil (Ts) samples were collected from Kegbara-Dere community in Gokana Local Government Area of Rivers State with sterile shovel from three different spots at the same location and put in black polythene bags and transported to the microbiological laboratory within 24 hours for physicochemical and microbiological analyses. Oil spill dispersant (OSD/LT and OSD/Seacare) were obtained from Baker and Hughes Nigeria Limited in Rivers state, Nigeria.
Methodology: Standard microbiological procedures were used to enumerate, isolate and identify the bacterial isolates. Pseudomonas aeruginosa and Bacillus megaterium in oil spill dispersants contaminated soil were monitored over a period of 1, 7, 14, 21 and 28 days respectively for their bioremediation potentials.
Results: The presence of Pseudomonas aeruginosa (Pa) or Bacillus megaterium(Bm) in oil spill dispersant polluted soils enhanced decrease in Total Hydrocarbon Content (THC) of the soil. THC for control soil reduced from 18348.68 mg/kg to 9111.84 mg/kg; TS+OSD/LT+Bm, 18348.68 to 7092.11 mg/kg; TS+OSD/LT+Pa, 18348.68 to 6263.16(mg/kg); TS+OSD/LT+Bm+Pa, 18348.68 to 2473.68 mg/kg; TS+OSD/SC+Bm, 18348.68 to 6421.05 mg/kg; TS+OSD/SC+Pa, 18348.68 to 5618.42 mg/kg; TS+OSD/SC+Bm+Pa, 18348.68 to 5835.53 mg/kg, between the first (day 1 ) and last day ( day 28). The percentage (%) bioremediation rate of polluted soil was as follows: control (TS(CRTL) 50.3%, TS+OSD/LT+Bm 61.3%, OSD/LT+Pa 65.9%, and OSD/LT+Bm+Pa 86.5% Whereas, TS+OSD/Seacare+Bm had 65.0%, OSD/Seacare+Pa 69.4%, OSD/Seacare+Bm+Pa 68.2% respectively. The highest percentages of THC in this study were from soil samples treated with oil spill dispersant and organisms while the least was observed in treatments without oil spill dispersant and organism. This suggests that microorganisms are more abundant in oil spill dispersant polluted soils than unpolluted soils.
Conclusion: From this study, it was observed that bioremediation of dispersant polluted environments could be achieved by stimulation of native microorganisms such as Pseudomonas aeruginosa KX828570 and Bacillus megaterium KY085976 and this would be cost effective in the clean-up strategy for such pollutants.