Bioremediation Potentials of Enterobacter cloacae Exposed to Crude Oil-impacted Soil
This study investigated the potential of an autochthonous bacterium (Enterobacter cloacae) isolated from the Nekede dumpsite in remediating crude oil-contaminated soil. The bioremediation experiment involved treating soil contaminated with 5% crude oil concentration with Enterobacter cloacae and monitoring soil physicochemical parameters, heavy metal concentrations. Standard analytical methods were used for physicochemical analyses and the following mean concentrations were obtained for pH, moisture content, conductivity, organic matter, TOC, Ca, NO3, PO4, P and NH3: 7.42, 2.34%, 110.0µS/cm, 3.27%, 4.30%, 196.14mg/L, 27.81mg/L, 6.82mg/kg, 1.84mg/kg and 1.329mg/kg in FUTO (control) soil; 6.50, 1.17%, 85.74µS/cm, 1.71%, 4.95%, 136.18mg/L, 38.18mg/L, 1.24mg/kg, 1.05mg/kg and 1.043mg/kg in FUTO soil + contaminant + treatment; 6.42, 1.78%, 107.48µS/cm, 3.24%, 4.81%, 134.5mg/L, 24.22mg/L, 4.78mg/kg, 1.83mg/kg and 2.067mg/kg in dumpsite soil; and 6.73, 1.55%, 100.5µS/cm, 1.14%, 5.08%, 134.14mg/L, 31.37mg/L, 2.44mg/kg, 1.12mg/kg and 0.196mg/kg in dumpsite soil + contaminant + treatment. The concentrations of heavy metals (Cr, Pb, Cu, Zn, Fe, Cd and Ni) in treated and untreated soil samples from FUTO and Nekede analyzed using Atomic Absorption Spectrophotometer obtained results showing the following mean concentrations: 50.45, 4.78, 18.13, 24.32, 10.2, 5.46 and 0.067 mg/kg in contaminated FUTO samples; 62.81, 8.11, 41.24, 23.85, 11.6, 6.86 and 0.054 mg/kg in uncontaminated Nekede samples and 74.11, 12.04, 49.07, 23.98, 14.8, 6.43 and 0.057 mg/kg in contaminated Nekede samples respectively. After bioremediation, the following mean concentrations were obtained: 35.21, 3.37, 9.52, 25.38, 7.2, 2.02 and 0.032 mg/kg in contaminated FUTO samples; 43.21, 5.11, 30.11, 24.79, 8.6, 4.23 and 0.027 mg/kg in uncontaminated Nekede samples and 51.83, 7.04, 32.07, 24.89, 9.8, 4.33 and 0.029 mg/kg in contaminated Nekede samples respectively. The findings from this study confirm that bioremediation with Enterobacter cloacae is effective in reducing heavy metal concentrations in crude oil-polluted soils.
Keywords: Bioremediation, Enterobacter cloacae, Crude oil-contamination, Imo State.
