Screening and Characterization of Hydrocarbonoclastic Bacteria Isolated from Oil-contaminated Soils from Auto Garages

Agnes Njoki Mwaura

doi:10.11648/j.ijmb.20180301.13

Abstract

Release of petroleum oil and its products into the environment is a worldwide concern. The present study focused on isolation, molecular identification, morphological and biochemical characterization of bacteria possessing hydrocarbon-degrading properties. The study also aimed at optimizing appropriate culture conditions for the isolates as well as screening for alkane hydroxylase enzyme. Out of twenty one microbes isolated, nine were selected based on their ability to utilize different hydrocarbons. The isolates were observed to mineralize heating oil, hexane, octane, toluene and diesel oil. PCR amplification of 16S rDNA gene revealed that the isolates belong to six different genera; Pseudomonas, Acinetobacter, Klebsiella, Enterobacter, Salmonella and Ochrobactrum. Based on their ability to degrade diesel oil, three isolates were selected and their growth conditions optimized. Optimum degradation was recorded at less than 1% substrate concentration, pH 7 and temperature range of between 30°C and 37°C and using yeast extract as nitrogen source. GC-MS analyses confirmed their diesel oil degrading properties. Alkane hydroxylase gene from one of the isolates (isolate 1C) was successfully amplified indicating its catabolic capabilities in degrading alkanes. Overall, the characterized isolates may constitute potential candidates for biotechnological application in environmental cleanup of petroleum contaminants.

Highlights

Petroleum-based products are a principle source of energy for industries and daily life, making them a vital commodity central to the global economy [1]
Selection of efficient hydrocarbon degraders based on the ability to grow in minimal media supplemented with heating oil was done
A total of twenty one microbes (20 bacteria and 1 fungus) were isolated from oil-contaminated soils sampled from garages around Ngara, Nairobi, Kenya

Summary

Introduction

Petroleum-based products are a principle source of energy for industries and daily life, making them a vital commodity central to the global economy [1] They originate from crude oil whose main constituents are hydrocarbon compounds derived from ancient algae and plant remains found in reservoirs under the earth’s surface [2]. Current conventional disposal methods of petroleum products include physicochemical techniques such as photo-oxidation, burying, dispersion, washing, incineration, thermal conversion and other pyrolysis techniques [5,7]. Many of these methods are expensive and can result in incomplete decomposition of oil products. Physicochemical methods such as volatization, photooxidation and chemical oxidation are rarely successful in rapid removal of hydrocarbon contaminants especially the aromatics [8]

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