452 Journal of Basic Microbiology 2009, 49, 452 – 462 © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.jbm-journal.com Research Paper Enzymatic characterization of 30 kDa lipase from Pseudomonas aeruginosa ATCC 27853 Lidija T. Izrael-Zivkovic 1 , Gordana Đ. Gojgic-Cvijovic 2 , Kristina R. Gopcevic 1 , Miroslav M. Vrvic 2, 3 and Ivanka M. Karadzic 1 1 School of Medicine, Department of Chemistry, University of Belgrade, Belgrade, Serbia 2 Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, Belgrade, Serbia 3 Faculty of Chemistry, University of Belgrade, Belgrade, Serbia An extracellular lipase from Pseudomonas aeruginosa ATCC 27853 has been purified and its enzymatic characteristics were determined. According to SDS-PAGE and gel filtration molecular mass estimated to be 30 kDa, what classified the lipase in group I.1. Although 14 lipases from P. aeruginosa with similar molecular mass are referred to date, their basic enzymatic properties have not been reported yet. To address the gap we found: the optimal temperature and pH in water solution being 50 °C and 9.3, respectively; the lipase was inhibited with Hg 2+ ions and sodium dodecylsulphate (SDS), while non-ionic detergent Triton X-100 activated the enzyme; the lipase hydrolyzed more rapidly middle chain triglycerides and it was not regiospecific; the lipase demonstrated naturally occurring stability in different organic solvents with concentrations ranging from 30 to 70%, including good thermal stability in 30% organic solvent solution. Even though strain P. aeruginosa ATCC 27853 was not isolated from extreme environment it showed activity in organic solvent suggesting that this lipase is suitable for variety of applications, including reactions in water restricted medium and bioremediation of contaminations by organic solvents. Keywords: Lipase / Pseudomonas aeruginosa / Organic solvents / Solvent free media Received: July 17, 2008; accepted: January 10, 2009 DOI 10.1002/jobm.200800229 Introduction * Pseudomonas aeruginosa is an opportunistic human pathogen which causes a variety of diseases, particu- larly in immuno-compromised patients [1]. Diverse infections are based on metabolic versatility and ability of P. aeruginosa to colonize and survive in different niches [2]. Many factors which contribute to Pseudomo- nas pathogenesis such as: resistance to antimicrobials, ability to form biofilms [3], synthesis of numerous exo- products most of which can act as virulence factors, being regulated by quorum sensing (QS), a cell-to-cell communication system, are well described in P. aeruginosa [4]. It was thought that only biofilm- Correspondence: Ivanka M. Karadzic, School of Medicine, Department of Chemistry, University of Belgrade, Visegradska 26, 11000 Belgrade, Serbia E-mail: ivankakaradzic@yahoo.com Phone: + 381-11-3615-773 Fax: + 381-11-3615-764 mediated infections that occur on medical devices such as catheters, dialysis machines, and orthopedic devices had clinical relevance, but there is now a clear evidence that P. aeruginosa as well exists in biofilm in the lungs of the patients with cystic fibrosis [5]. Forming biofilms as specific communities of cells encased in an extracel- lular matrix composed of proteins, nucleic acids, and cell debris, P. aeruginosa obtains competitive advantage in invasion of a host and in survival in different envi- ronments. It has recently, become clear that numerous exoproducts including: elastase, LasA protease, alkaline protease, phospholipase C, lipase, exotoxin A, rham- nolipids can act as virulence factors which are con- trolled by QS, and moreover that QS is important in the development of P. aeruginosa biofilms [6]. With the in- creasement of knowledge of the importance of biofilms and QS in bacterial pathogenesis, increases a need to discover a new alternative approaches to the therapy of bacterial infections on the level of exoproduct forma-