Romanian Biotechnological Letters Vol. 18, No.3, 2013 Copyright © 2013 University of Bucharest Printed in Romania. All rights reserved ORIGINAL PAPER 8372 Romanian Biotechnological Letters, Vol. 18, No. 3, 2013 Characterization of Pseudomonas strains with hydrocarbons-degrading potential Received for publication, February 26, 2012 Accepted, May 15, 2013 ROBERTINA IONESCU 2* , ANA-MARIA TANASE 1 , TATIANA VASSU 1 , DIANA PELINESCU 1 , IULIA CHICIUDEAN 3 , ORTANSA CSUTAK 1 , ILEANA STOICA 1* 1 Department of Genetics, University of Bucharest, Bucharest, Romania 2 PhD student, Department of Genetics, University of Bucharest, Bucharest, Romania 3 M.Sc. student, Department of Genetics, University of Bucharest, Bucharest, Romania * Author to whom correspondence should be addressed: E-mail: prutu@yahoo.com, ionescu_robertina@yahoo.com Tel: + 40213118077 Abstract In order to obtain hydrocarbon-degrading strains, we isolated several bacterial strains from crude oil and oil polluted soil. These isolates had maximum growth on 1% of n-hexadecane and Fluka- oil, results that was confirmed by the presence of alkB-gene. Biolog identification System showed that our newly-isolates are affiliated to Pseudomonas aeruginosa group and also to Pseudomonas fluorescens group, and much more comparative analysis of phenotypic and genotypic dendrograms showed that strains are very similar but not identical. Keywords: n-alkanes, oil, alkB genes, chemotaxis, BIOLOG, ARDRA Introduction One of the major pollutants of the environment is the oil and, respectively, the oil waste products. Crude oil is one of the most complex mixtures formed naturally, which contains more than several hundred compounds. In chemical terms these compounds can be divided into four classes: the most frequent are saturated hydrocarbons (linear or branched alkanes, cycloalkanes), aromatic hydrocarbons, asphaltenes (phenol, fatty acids, ketones, esters, porphyrins) and resins (pyridines, quinolines, sulfoxides, amides) [4], [1]. Regarding their susceptibility to microbial attack, these hydrocarbons can be classified as follows: linear alkanes > branched alkanes > small aromatics > cyclic alkanes > polar compounds > asphaltenes [7]. Throughout time people have developed several methods for cleaning polluted sites, but one the most successful solution makes use of indigenous microorganisms [8]. Bioremediation studies of oil polluted ecosystems have shown that bacterial genera with significant biodegrading capacity are: Arthrobacter, Burkholderia, Mycobacterium, Pseudomonas, Sphingomonas, Rhodococcus [2]. Pseudomonas species are ubiquitous bacterial species, known to be able to use hydrocarbons as sole carbon and energy source, found in various ecological niches, even in oil polluted soil and water. Thus, the ecological diversity of these bacteria is probably due to the ability to metabolize various substrates. In our experiments we have isolated several strains of Pseudomonas from oil polluted soil and from crude oil, with hydrocarbon-degrading abilities. We evaluated the degrading potential by chemotaxic response toward n-hexadecane and crude oil and also by growth quantification having n-hexadecane and oil (1%-6%) as single carbon source and energy. Molecular analyses regarding the presence of alkane hydroxylase genes (alkB) allowed us to correlate the phenotypic and genotypic traits.