South Asian Journal of Research in Microbiology

The effectiveness of Pseudomonas aeruginosa, Aspergillus niger and the consortium of these two bioremediants in remediating soils polluted with crude oil was studied. Soil samples were contaminated with different levels of crude oil (4%V/W of crude oil -0.2kg/5kg of soil 80,000kg/ha; 8%V/W of crude oil -0.4kg/5kg of soil = 160,000kg/ha; and 12%V/W of crude oil =0.6kg/5kg of soil 240.000kg/ha), the contaminated soils were inoculated with three different concentrations (50mls, 100mls and 150mls) of the bioremediants, these were left to stand for three months (90 days), and the total hydrocarbon content (THC), was measured at the start (day 0) and at the end (day 90) of the experiment. Results showed that the 4% V/W setups had the highest level of bioremediation when inoculated with a consortium of 150mls of Pseudomonas aeruginosa and 150mls of Aspergillus niger, reducing the THC considerably (from 7200 to 3600mg/kg).This demonstrates how bacteria and fungi work together to break down the contamination in soil polluted with crude oil. A decrease in THC of the contaminated soil inoculated with the two bioremediants both alone and in consortium (150mls each of Pseudomonas aeruginosa and Aspergillus niger, which is also their recommended application rate) was also recorded, indicating their strong potential in the breakdown of crude oil. The combined use of Pseudomonas aeruginosa and Aspergillus niger as bioremediants, rather than their individual usage, is recommended as a preferable method for remediating soil contaminated with crude oil. This will be vital in oil spill management and remediation especially in the Niger Delta region of Nigeria.