Characterization of Autochthonous Bacterial Isolates with The Potentiality to Degrade Spent Engine Oil from Contaminated Soil Area Enriched with <i>Glycine max</i>

Abstract

This study was conducted to identify and characterize bacteria capable of degrading spent oil contaminated soil. The physicochemical parameters of used engine oil were analyzed according to existing standards, while the total heterotrophic plate counts (HBC) and hydrocarbon utilizing bacteria counts were ascertained with the pour plate methods using nutrient agar and minimal salt agar (MSA) media respectively. The results indicated a mean total HBC ranging from 2.86 ± 0.08 to 5.76 log10 CFU/g and mean hydrocarbon utilizing bacterial counts from 1.32 ± 0.09 to 3.82 ± 0.25 log10 CFU/g, with samples enriched with Glycine max (Soybean) recorded to have the highest bacterial counts. The phenotypic identification of the hydrocarbon utilizing bacteria as sources of carbon and energy showed the presence of two primary bacterial genera: Bacillus and Micrococcus.
However, from the overall 50 counted colonies, the frequency of occurrence for Bacillus was 41 (82 %) whereas, the Micrococcus was (9) 18%. The obtained data, confirmed the breakdown capacity of autochthonous (indigenous) organisms notably; Bacillus in the reduction of pollutants linked with oil spillage. This provides for reliable and promising approach of ameliorating crude oil pollutants and its inherent threats.

Keywords: Soil, spent oil, Glycine max, degrading bacteria, isolation and bioremediation