Biodegradation of spent engine oil by bacteria isolated from the rhizosphere of legumes grown in contaminated soil

Abstract

Biodegradation of spent engine oil (SEO) by bacteria isolated from the rhizosphere of Cajan cajan and Lablab purpureus was investigated. It was with a view to determining most efficient bacterial species that could degrade SEO in phytoremediation studies. Hydrocarbon degrading bacteria were isolated and identified by enrichment culture technique using oil agar supplemented with 0.1% v/v SEO. Total heterotrophic and oil utilizing bacterial count showed the occurrence of large number of bacteria predominantly in the rhizosphere soil, ranging between 54×10 8 -144×10 8 CFU/g and 4×10 8 -96×10 8 CFU/g respectively. Percentage of oil utilizing bacteria ranged between 0% (uncontaminated non rhizosphere soil) to 76% (contaminated rhizosphere). Turbidimetrically, five bacterial species namely Pseudomonas putrefacience CR33, Klebsiella pneumonia CR23, Pseudomonas alcaligenes LR14, Klebsiella aerogenes CR21, and Bacillus coagulans CR31 were shown to grow maximally and degraded the oil at the rate of 68%, 62%, 59%, 58%and 45% respectively. Chromatographic analysis using GC-MS showed the presence of lower molecular weight hydrocarbons in the residual oil (indicating degradation) after 21 days, whereas the undegraded oil (control) had higher molecular weight hydrocarbons after the same period. The species isolated were shown to have high ability of SEO biodegradation and therefore could be important tools in ameliorating SEO contaminated soil.

Biodegradation of crude petroleum by bacterial consortia from oil-contaminated soils in Ota, Ogun State, South-Western, Nigeria

“…The high capability of Bacillus sp. isolated from the soil in degrading crude oil has been repeatedly observed in both contaminated and uncontaminated soils (Mohamad et al, 2004;Ismail et al, 2014).…”

Biostimulation Potentials of Vigna Species (L.) in Hydrocarbon Impacted Soil

“…Soil samples were aseptically collected from the rhizosphere of both plants for enumeration of total heterotrophic and oil utilizing bacteria as described by [16]. Total heterotrophic bacteria were enumerated by inoculating serially diluted (×10 8 ) soil samples in nutrient agar (Oxoid) after 24 hours incubation while used engine oil degrading bacteria were enumerated and subsequently isolated by inoculating similar dilution into oil agar (composed of 1.2g KH 2 PO 4 , 1.8g K 2 HPO 4 4.0g NH 4 Cl, 0.2g MgSO 4 .7H 2 O, 0.1gNaCl, 0.01g FeSO 4 .7H 2 O and 20g agar per liter at pH 7.4) supplemented with 0.1% UEO, after 5 days.…”

Experimental Investigation of Sophorolipid Biosurfactants Produced by Candida and Pleurotus Species Using Waste Oils and Rice Bran and Their Oilfield Benefits

“…The biosurfactants concentrate appeared as dirtywhite or brown crystals. Sophorolipid yield was estimated gravimetrically and expressed in g/L [29].…”