Effects of spent hydrocarbon on bacteria population

Abstract

This study aimed at the effect of spent hydrocarbon contamination on microbial population in soil. Standard microbiological methods were used to determine the total heterotrophic count hydrocarbon utilization, isolation and identification of bacterial and effect of pH and spent hydrocarbon concentration on bacterial. The total heterotrophic bacterial count (THB) ranges from 6.2 ± 0.13 x106 to 3.2± 0.10 x106 cfu/g. The total hydrocarbon utilizing bacterial count ranges from 3.2 ± 0.13 x106 to 1.2± 0.10 x106 cfu/g. The bacterial isolated were Bacillus subtilis, Pseudomonas flourescens, Klebsiella aerogenes and Proteus hauseri. It was observed that Bacillus subtiliis had the highest occurrence from location E (50.0%). Pseudomonas flourescens from location A and B (33.3%) and Proteus hauseri had the highest occurrence from location C (66.6%). The effect of pH on bacterial growth rate analyzed showed that Bacillus subtilis had the highest turbidity at pH 6.5 (0.511 ± 0.15 nmm), Klebsiella aerogenes had the highest turbidity at pH 7.5 (0.233 ± 0.33nm), Pseudomonas flourescens was at pH 6.5 (0.723 ± 0.61 nm) and Proteus sp recorded highest turbidity at pH 6.5 (0.373 ± 0.22nm) followed by pH 5.5 (0.237 ± 0.19 nm). The effect of spent hydrocarbon concentration showed that Bacillus subtilis recorded highest turbidity at 10% concentration (0.744 ± 0.03 nm), Klebsiella aerogenes recorded highest at 10% concentration (0.321 ± 0.21 nm), Pseudomonas flourescens was at 10% concentration (0.887 ± 0.23 nm) and Proteus sp recorded highest turbidity at 10% concentration (0.378 ± 0.13 nm). From this study it was observed that indigenous bacterial had the ability to utilized the spent hydrocarbon if the pH of the soil is regulated.