Aim: To degrade the crude oil polluted soil with silver particles synthesized by some Gram negative rhizosphere bacteria of cocoa, orange and timber obtained from Idanre, Ondo State, Nigeria. Place and Duration of Study: Soil samples were obtained from Idanre, Ondo State while crude oil polluted soil samples were obtained from Zion town in Ese- Odo at Ilaje, Ondo State, between June and September 2018. Also, Bonnylight Crude oil was collected from Warri in Nigeria. This research work was carried out at the Department of Microbiology Laboratory, Federal University of Technology, Akure. Methodology: Soil samples (rhizosphere) were collected in sterile polythene bags and tightly packed and transported for analysis. The types and loads of bacteria present in the soil samples were determined. Identification and characterization of various bacterial isolates were based on Gram staining techniques and different biochemical tests. The physicochemical properties of the crude oil polluted soil were determined. The microbial biomass and the synthesis of silver particles were carried out while the bioremediation of the crude oil polluted soil with the silver particles which were performed in triplicate. Also, bioremediation of crude oil with the bacterial isolates were performed in triplicate. Five millilitres (5 ml) of silver particles produced was inoculated into 50 g of sterilized crude oil polluted soil in a plastic container with 5ml of basal medium and 3 ml of the harvested cells of the isolates was inoculated into 10 ml of the basal medium with 30ml of crude oil in a conical flask. The unsterilized soil without inoculum and silver particles were served as control, also crude oil without inoculum and silver nanoparticles were served as a control. Results: Citrobacter freundii, Yersinia pestis, Edwardsiella tarda, were isolated from rhizosphere of cocoa. Serratia marcescens, Providencia stuatii were isolated from rhizosphere of orange while Enterobacter agglutinate, Moellerella wisconsis were isolated from rhizosphere of timber. The silver particles bioremediation on polluted soil ranges were recorded within 5 days interval for 30 days. It was deduced that Enterobacter sp appeared to be the fastest on polluted soil followed by Citrobacter sp, Providencia sp, Serratia sp and Yersinia sp. Conclusion: Findings from this study revealed the effects of rhizosphere Gram negative bacteria in cleaning up crude oil polluted soil environment and the usefulness of silver particles in remediating hydrocarbon polluted soil.

Degradation of crude oil by bacteria isolated from three plantations soil at Idanre, Nigeria were comparatively investigated. Soil samples collected by hand trowel at 5cm rhizosphere of Cocoa, Orange, and Teak plantations from Idanre, Ondo State. The crude oil – forcados blend was obtained from Warri, Delta State, Nigeria. Gram negative bacteria were isolated from rhizosphere soil sample using standard microbiological methods. Preparation of Biomass was done by centrifuging nutrient broth repeatedly to wash cells. Harvested cells were obtained for the degradation of crude oil. Harvested cells were inoculated with crude oil and then incubated in a shaker. Degradation of crude oil was monitored by using spectrophotometer to read the OD at 540 nm.  The bacteria isolated from rhizosphere of cocoa include: Citrobacter freundii, Yersinia pestis, Edwardsiella tarda,. Serratia marcescens. Rhizosphere of orange; Providencia stuatii while Enterobacter agglumerans, Moellerella wisconsis were isolated from rhizosphere of teak. The most effective hydrocarbon utilizing bacteria was Enterobacter agglumerans, which resulted in increase in population densities and reduction in hydrocarbon contents in the crude oil. Findings from this study shows the effectiveness of degrading hydrocarbon in liquid medium and further confirmed the potency of bacterial cells to degrade crude oil.