Enhancing Biodegradation of Spent Oil in Soil through Autochthonous Bioaugmentation

The study used autochthonous bio-augmentation for the bio-degradation of spent oil in soil via standard non-molecular analysis. These organisms were reintroduced individually and in synergy into microcosms of the contaminated soil so they can use the spent oil as food, carbon and energy sources. The results revealed the presence of seventeen (17) bacteria in the contaminated soil. The performance of the individual bacteria accounted for 67.60% of the total variance in the extracted residual oil following bio-augmentation with the inherent microbes while the days of bio-augmentation accounts for 23.16% of the total variance, p< 0.001. However, the days allowed for autochthonous bioaugmentation with microbes in synergy to occur , caused 47.89% of the total variance in the amount of residual oil extracted, p<0.001 while the different mixed bacteria used accounted for 35.03% of the total variance, p <0.001. At the end of the 42-day incubation period, the performance of Bacillus spp. >Clostridium spp. >Staphylococcus spp. in their microcosms were significantly better than the rest of the bacteria isolated from the contaminated soil. Also, Micrococcus spp. + Citrobacter spp., Clostridium spp. + Citrobacter spp. and Mycobacterium spp. + Salmonella species in their respective microcosms performance significantly better than the rest mixed bacteria, p<0.05. The individual bacteria and in synergy performed significantly better than the natural attenuated microcosms in reducing the amount of residual oil obtained with p values< 0.001. Increasing the days of bioaugmentation will also increase the effectiveness and efficiency of the bacteria. Thus, the application of autochthonous bio-augmentation with these tried species of bacteria for further studies in a larger scale may be helpful to reduce the pollution of the environment with spent oil.