Bacteriological and Physicochemical Profiles of Soils in Selected Oil-Contaminated Sites in Yorla, Ogoni Land

Abstract

Bacteriological and physicochemical properties of oil–polluted sites in Yorla, Ogoniland was studied. Soil samples were collected from three different points and analyzed for bacteriological and physicochemical characterization using standard methods. The total culturable heterotrophic bacteria (THC) counts from the polluted sites ranged from 7.2. *107to9.5*107cfu/g while the THC of the unpolluted sites ranged from 11.9 *107 to 12.9 *107cfu/g. Hydrocarbon utilizing bacterial (HUB) counts from the polluted sites ranged from 2.8 *106 to 3.3 * 106cfu/g while the hydrocarbon utilizing bacterial (HUB) counts of the unpolluted sites ranged from 1.1 *106to 1.5 *106.Bacteria obtained from the various sites were isolated using standard microbiological methods. Identification of isolates was carried out using 16S rRNA (Ribonucleic acid) gene amplification and sequencing. Electropherograms of generated sequences were inspected with Chromas Lite 2.0.1 software. Sequence identification was carried out using GenBank’s Basic Local Alignment Search Tool (BLAST) algorithm of National Centre for Biotechnology and Information (NCBI). Sequence analysis revealed the presence of Acinetobacter venetianus , Bacillus cereus, Bacillus flexus, Bacillus thuringiensis, Acinetobacter junii, Shewanella sp., Lysinibacillus xylanilyticus and Pseudomonas pseudoalcaligenes,  The physicochemical properties of the soil samples analyzed showed that the pH values of the polluted sites ranged from 7.86 to 9.16 while those of  the unpolluted sites were 6.19 and 7.10. Total organic carbon (TOC) contents of the polluted sites ranged from 3.18% to 3.96% while the unpolluted sites TOC ranged from 3.00% -3.06%. Statistical analyses of the results were carried out using analysis of variance (ANOVA) and t-test analysis. This work revealed the presence of reasonable population of indigenous hydrocarbon-utilizing bacteria in oil-polluted sites in Yorla community which can be monitored and enhanced to improve their bioremediation abilities in the oil-polluted sites.