Abstract

Twenty seven potential hydrocarbon degrader bacterial isolates were isolated from soil that has been exposed to crude petroleum oil. The hydrocarbon degradation potentialities of these isolates were assessed against n-tetradecane. Four isolates (AT3, AT5, AT11 and AT15) were the most potent isolates. These isolates were identified via morphological, biochemical and 16S-rRNA gene sequencing techniques as (Pseudomonas stutzeri, Bacillus thuringiensis, Bacillus pumilus and Bacillus cereus), respectively. AT3 isolate was the highest n-tetradecane degrader. This isolate exhibited specific growth rate in Bushnell-Hass medium amended with hydrocarbon, n-tetradecane of 1.213 h^-1 and growth yield of 1.311 g cells g hydrocarbon^-1. An efficient biodegradation up to 90% was performed by AT3 bacterial isolate. Genetic fingerprinting was carried out using RAPD-PCR and SDS-PAGE methods to characterize and conduct phylogenetic relationship among the four most potent isolates. Thirty six specific markers were obtained and used to characterize the four studied isolates. Different specific markers for AT3 isolate were generated. The closest genetic distance was found between isolate AT11 and AT15 (0.55), while the lowest genetic similarity was between AT3 and AT5 (0.41). The introduced markers could be used for tracking the most potent isolates.

Key words: Genetic fingerprinting, hydrocarbon, bacterial isolate, biodegradation, P. stutzeri, B. thuringiensis, B. pumilus, B. cereus.