Ecological Proxies to the Bioremediation of Crude Oil Polluted Mangrove Soil Obtained from Okerenkoko, Delta State, Nigeria

The impact of pollutants on the mangrove ecosystem has caused several ecological challenges to man and his quest to survive. The activities of illegal oil exploitation and the regulatory agencies have impeded the success of reducing the presence of pollutants in the ecosystem. The mangrove soil samples were obtained from the creeks of Okerenkoko, Delta State, Nigeria and transported to the laboratory. Physicochemical components were determined using analytical grade reagents and procedures. Agro waste was obtained from the markets, slaughterhouses and mills and processed into portions for the bioremediation study. The earthen pots were prepared using 5kg of the polluted soil obtained from the study area using 10% oil palm empty fruit bunch ash, 20% Rumen waste and 30% wood shavings. The study identified a 90% reduction in total petroleum hydrocarbons using the composite in the experiment with composite mixtures of the feedstock. The total heterotrophic bacterial count increased from 6.8 Log10 CFU/g to 8.8 Log10 CFU/g while the soil pH increased from 6.2 to 6.7. The predominant flora consisted of Bacillus sp., Aeromonas sp., and Pseudomonas sp. After the 8th week of the study, Pseudomonas sp. and Staphylococcus sp. were identified as playing a crucial role in achieving the reduction of the pollutant. Molecular investigations revealed that the isolates obtained were Bacillus axarquiensis and Pseudomonas guguanensis, with 100% similarity with the already deposited organisms in the GENBANK. This study has shed light on the potential of using readily available biomass and feedstock in the resolution of our environmental challenges.