Bacterization of spent engine oil impacted tropical garden soil hydrocarbon for degradation and bioremediaton

Spent engine oil has significant negative impact on microbial communities in soil and water; this disruption can have cascading effects on various ecosystem processes, such as nutrient cycling, nitrogen fixation, carbon sequestration, and the degradation of organic matter. This study investigates the hydrocarbon degradation potentials of Alcaligenes aquatilis isolated from adjoining farmland to the Mechanic Village, Uyo, Akwa Ibom State, Nigeria. Bioremediation was monitored using the percentage ratio of total petroleum hydrocarbons (TPH) at day 0 to Total Residual Hydrocarbons (TRH) after 56 days treatment by gas chromatography- mass spectrometry (GC-MS) techniques. Over 97.77 %, 98.08 %, 95.91 %, and 98.47 %, of the total petroleum hydrocarbons fractions of the spent engine oil contamination at 5 %, 10 %, 15 % and 20 % concentration were respectively degraded in 4 kg of garden soil augmented with Alcaligenes aquatilis. Statistical analysis (ANOVA) showed highly significant difference (p<0.001) in TPH content between the mean initial and residual TPH. Monitored natural attenuation showed the highest percentage degradation (marginal increase) of about 98.79 % at 5 % contamination with spent engine oil. The molecular characteristics of the best degrading bacterial strains by PCR, sequencing and blasting suggest the isolates as, Alcaligenes aquatilis strain 4p171492R. Based on the results of this work A. aquatilis strain 4p171492R showed strong degradative activity and is strongly recommended for the clean- up and bioremediation of spent engine oil impacted soil in contaminated sites.