ABSTRACT

Petroleum hydrocarbon-degrading bacteria are ubiquitous in nature and can utilize hydrocarbon as sources of carbon and energy. Bacteria with such capabilities are often exploited for the bioremediation of petroleum oil contaminated environments. Petroleum degradation potential of bacteria isolated from automobile mechanic workshop was carried out.  A total of five samples of oil contaminated soil were collected weekly for five weeks. The samples were taken immediately to Microbiology laboratory of Madonna University Elele for analysis. The media used were Bushnell Haas agar, Mineral salt medium and Nutrient agar. The method used for isolation were serial dilution, pour plating and vapour phase transfer techniques. Colonial morphology, Gram staining and biochemical tests were carried out using the standard microbiological methods. Also genomic DNA were quantified, PCR was carried and the DNA were sequenced. Physicochemical parameters of the soil sample were also analyzed. The mean count log10 cfu/ mL of petroleum utilizing Bacteria ranges from 4.05±0.22 – 4.11± 0.22 for petrol, 4.06± 0.1 -4.11± 0.1 for diesel and 4.05± 0.2 – 4.11±0.2 for brake fluid. The total aerobic plate count mean count log10 cfu/ mL ranged from 5.05± 0.1 -5.16 ± 0.2. For physicochemical parameters analyzed, temperature ranged from 28.30- 29.60o C, pH ranged from 5.60 -6.96, Conductivity, 13.7 -860µs/cm, Total organic carbon 0.32-2.23%, Total nitrogen 0.13-0.19%, Phosphate 0.98-1.80 mg/kg,Iron 15.1-320 mg/kg , Potassium 6.00 -13.60mg/kg ,Calcium 108-690 mg/kg, Magnesium 152-388 mg/kg, Zinc 0.12-18.20 mg/kg, Manganese 9.20 -60.40 mg/kg and Copper <0.10- 1.70 mg/kg also Chromium ranged from 0.40 -10.50mg/kg, Lead <0.10-1.40 mg/kg,  Barium < 0.10-0.18 mg/kg, Nickel < 0.10 -0.25 mg/kg, Cadmium<0.10 mg/kg, Mercury <0.10 mg/kg, Oil and grease 1.5-128 mg/kg, Total petroleum hydrocarbon 4.5-196 mg/kg  and moisture 0.25 -0.39%. The hydrocarbon utilizing Bacteria isolated and their percentage occurrence were Pseudochrobactrum asaccharolyticum 24.5%,  Empedobacter brevis28.6%, Lysinibacillus macroides24.5% and Neisseria  weaveri 22.5%. The percentage occurrence of total aerobic plate count were Pseudochrobactrum asaccharolyticum 15.0%, %, Empedobacter brevis20.4%, Lysinibacillus macroides17.2% and Neisseria weaveri18.3%, Azotobacter sp 14.0% and Clostridium sp 15.1%. Statistical analysis of the results were done using ANOVA and least significant difference(LSD). Some bacteria such as those isolated in this research have the potential to utilize hydrocarbons as sole source of carbon and energy to survive in such environment thereby breaking down or degrading the hydrocarbon.