Characterization of hydrocarbon-degrading bacterial strains isolated from oil-polluted soil Ana-Maria Tanase, Robertina Ionescu, Iulia Chiciudean, Tatiana Vassu, Ileana Stoica * Department of Genetics, University of Bucharest, Bucharest, Intr. Portocalelor No 1, Sector 6, Bucharest 060101, Romania article info Article history: Received 1 February 2012 Received in revised form 22 May 2012 Accepted 22 May 2012 Available online xxx Keywords: Biolog 16S rDNA n-hexadecane n-alkane-hydroxylase alkB Achromobacter xylosoxidans abstract Using enrichment culturing method, a microbial population was detected in an oil-contaminated soil nearby an extraction field. Isolated strains were able use medium-length n-alkanes as sole carbon and energy source as assessed by growth experiments. Results showed a high diversity among strains at molecular level, and also in the metabolic profiles. Physiological and biochemical tests showed a simi- larity within a group of four strains, as confirmed by Biolog MicroLog analysis. Based on 16S rDNA sequences strains were identified as Rhodococcus erythropolis, Acinetobacter baumanii, Burkholderia cepacia and Achromobacter xylosoxidans. Alkane monooxygenase gene (alkB) was successfully detected in all our strains and for the first time alkB genes were found in an A. xylosoxidans strain. This bacterial species has been previously reported as part of microbial communities from oil polluted environments, but there are few studies that address mechanisms details of A. xylosoxidans involvement in n-alkane degradation process. Ó 2012 Published by Elsevier Ltd. 1. Introduction Almost all human activities rely on petroleum as a major source of energy, but its industrial use can produce environmental disas- ters (Atlas and Bartha, 1992; Liu et al., 2010). Petroleum’s complex composition arises from the large range of hydrocarbons e from aliphatics to polyaromatics e and provides a large set of carbon sources for the development of complex microbial communities in oil-polluted environments (Leahy and Colwell, 1990; Van Hamme et al., 2003). Although many microorganisms are able to degrade aliphatic hydrocarbons and have been isolated from various contaminated and uncontaminated sites, relatively little is known about the genetic characteristics of their alkane-degradative systems (Rojo, 2009). Aerobic degradation of alkanes can be carried out by two major types of enzymes: the alkane monooxygenase (also known as alkane hydroxylase, or AlkB), and certain cytochrome P450 systems (van Beilen et al., 2006). Since 1994, when van Beilen et al. first described alkane mono-oxygenase in a Pseudomonas strain, such enzymes have been found in many bacterial genera: Rhodococcus (Sameshima et al., 2008), Pseudomonas (Johnson and Hyman, 2006), Acinetobacter (Throne-Holst et al., 2007), Alcanivorax (Liu and Shao, 2005), Burkholderia (Mohanty and Mukherji, 2008), Geobacillus (Vomberg and Klinner, 2000), and Gordonia (Kato et al., 2009). Genes coding for the proteic complex alkane- monooxygenase have been thoroughly investigated and several authors (Whyte et al., 1998; Smits et al., 1999; Kloos et al., 2006; Powell et al., 2006) have proposed molecular methods for the detection of such genes, even at the microbial community level. Despite all this research, regulation of gene expression coding for alkane-degradation pathways still has many unsolved issues, especially because in many cases genes from central cellular metabolism are also involved (Paisse et al., 2011). In order to understand how alkanes are degraded in natural environments it is important to elucidate these complex mechanisms and the diverse metabolic pathways in new microbial isolates having hydrocarbon- degrading abilities (van Beilen et al., 2003; Rojo, 2009). In this study we focused on several bacterial strains isolated from an oil-enrichment culture, using oil-polluted soil samples as inocula. Our aim was to investigate the microbial capacity to use n-alkanes as sole carbon source and also the taxonomic identifi- cation by 16S rDNA sequences correlated with phenotypic profiles based on the Biolog system. We also performed a PCR screening test in order to detect the presence of alkB, the n-alkane hydroxylase gene. * Corresponding author. Tel./fax: þ40 21 3118077. E-mail addresses: geneticuss@yahoo.com (A.-M. Tanase), ionescu_robertina@ yahoo.com (R. Ionescu), bindu1384@yahoo.com (I. Chiciudean), vassut@ yahoo.com (T. Vassu), prutu@yahoo.com (I. Stoica). Contents lists available at SciVerse ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod 0964-8305/$ e see front matter Ó 2012 Published by Elsevier Ltd. http://dx.doi.org/10.1016/j.ibiod.2012.05.022 International Biodeterioration & Biodegradation xxx (2012) 1e5 Please cite this article in press as: Tanase, A.-M., et al., Characterization of hydrocarbon-degrading bacterial strains isolated from oil-polluted soil, International Biodeterioration & Biodegradation (2012), http://dx.doi.org/10.1016/j.ibiod.2012.05.022