Abstract

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An explosion in the world’s population has led to an increase in the demand for crude oil and its products resulting in an increased environmental pollution and thus leading to loss in biodiversity. Environmental reclamation by natural technique is believed to be eco-friendly and cost effective. This research investigated the biodegradation of crude oil supported on different soil particle sizes. Soil samples were randomly collected from different locations within Botanical garden of BUK and sieved into four (4) different particle sizes (0.6mm, 0.3mm, 0.15mm and 0.075mm) 200g of each of the sieved soil particle sizes were weighed and introduced into masonjar bottle. These were then uniformly contaminated with 60ml of crude oil. The set up were replicated in triplicate with each having two (2) controls. They were incubated aerobically at 37oC for 56 days. Enumeration of total aerobic heterotrophic bacteria (TAHB) was done on Nutrient agar (NA) and hydrocarbon utilizing bacteria (HUB) on Bushnell’Haas medium (BHM) supplemented with crude oil. The bacterial isolates were identified based on Grams reaction and biochemical tests. The degradation efficiency was confirmed by GC-MS analysis, which indicated that the microbial isolates utilized most of the crude oil components. The result shows that the mean microbial counts for both TAHB decrease from 5.93 ± 0.1 to 5.38 ± 0.08 x105cfu/g during 56 days period of the study. The result also shows an increase in the mean counts of HUB from 0.00 ± 0.0x103 to 3.74 ± 0.03x103 cfu/g. Particle size A has the highest increase. The HUB identified were Bacillus spp., Pseudomonas spp., Staphylococcus spp., Escherichia coli and Proteus spp. The results indicate that larger particle size favors faster hydrocarbon biodegradation.

Keywords: Reclamation, Biodegradation, Hydrocarbon