Phytoremediation of Oil-Contaminated Soils by Combining Flowering Plant Cultivation and Inoculation with Acinetobacter junii Strain M-2

Oil contamination of the soil by petroleum products has become an enormous environmental problem. In this study, we examined whether remediation of oil-contaminated soils by cultivating three flowering plants (Mimosa, Gazania, and Zinnia) could be enhanced by inoculation with Acinetobacter junii strain M-2 at different plant growth stages (at sowing, at early growth, and at mid-growth). The growth of Zinnia cultivated in oil-contaminated soils inoculated at sowing was significantly superior to that in the non-inoculated soil. Although total petroleum hydrocarbon concentrations in soils inoculated at sowing were nominally lower than those in non-inoculated soils, especially in the case of Zinnia planting, the effect did not reach statistical significance. However, dehydrogenase activity was significantly higher in the soils inoculated with A. junii strain M-2 than in non-inoculated soils for all three plant species tested. These results demonstrate that a combination of ornamental plant cultivation (particularly Zinnia) and inoculation with A. junii strain M-2 increases the efficiency of oil-contaminated soil phytoremediation.