Diversity of culturable aerobic bacteria colonizing four petroleum by-products storage reservoirs

The petroleum reservoirs are commonly exposed to bacterial contamination. The proliferation of several bacterial species, could modify the product quality, change viscosity, help other sulfate-reducing, iron reducing bacteria to grow, and accelerate reservoir biocorrosion. Thus, companies of storage and transport of petroleum frequently use biocides to prohibit bacterial proliferation. However, the use of the appropriate biocide, need an obvious knowledge of bacterial population harbouring the reservoir. Thus, in this study, we intended to isolate and identify the aerobic bacterial population existing in different reservoirs of petroleum derivatives in the refinery of Bizerte, Tunisia. The isolation and identification of these microorganisms may be of great interest in bioremediation of polluted sites. Besides, it could inform about hydrocarbon specificity of these microorganisms and therefore lead to the use of suitable biocides to clean these storage reservoirs. 25 different bacterial strains were isolated from water collected from reservoirs of crude oil, gasoline, diesel oil and kerosene. The different strains were identified using morphological and biochemical characterization, as well as sequencing of 16S rRNA. The systematic study of these strains showed that they belong to six different genera. The highest strain number was affiliated to the genera of Pseudomonas and Bacillus followed by genera of Staphylococcus, Enterobacter Comamonas and Paenibacillus. The results of this study are discussed in terms of the ecological significance of these microorganisms in relation with physico-chemical conditions of reservoirs and hydrocarbon composition. Key words: Bacterial diversity, storage reservoirs, phylogenetic relationships.