Assessment of the Phytoremediation Activity of the Rhizobacterial Flora of Arachis hypogaea (Groundnut) on Hydrocarbon Contaminated Soil

Abstract

Over the years, Nigeria’s development has accelerated due to crude oil exploaration. In spite of its enormous benefits, it has wreaked much havoc and damage on the ecosystem due to its toxicity. The study evaluated hydrocarbon degradation potentials by the rhizobacterial flora of the legume Arachis hypogaea (Groundnut) grown in potted sandy-loamy soil samples in the green house of Kebbi State University of Science and Technology, Aliero, Nigeria. Crude oil concentrations of 0.5, 1.0, 2.0, 2.5, 5.0, 10.0, 15.0, and 20.0mls were used to contaminate the soil samples respectively. All soil samples apart from the control were polluted. Groundnut germinated after seven days at concentration of 0.0 to 2.5% but at higher concentration of 5.0% of the contaminant, the germination time increased to nine days and at concentration 20%, it increased to ten (10) days. Even though groundnut germination was observed in all concentrations of crude oil tested, significant shoot retardation still occurs in both legumes consequent on crude oil toxicity. Rhizobacterial population also diminished with increase in crude oil concentration. The rhizobacterial population diminished with increase in crude oil concentration. The rhizobacteria isolated from the soil sample include Bacillus subtilis, Clostridium tetani, Staphylococcus aureus, Proteus vulgaris, and Enterobacter aerogenes. Rhizobacterial population also diminished with increase in crude oil concentration. The study revealed the resistance of groundnut to crude oil (p<0.05), marking groundnut out as a promising phytoremediation plant.