160 Journal of Basic Microbiology 2008, 48, 160 – 167 © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.jbm-journal.com Research Paper Production of an extracellular thermohalophilic lipase from a moderately halophilic bacterium, Salinivibrio sp. strain SA-2 Mohammad Ali Amoozegar 1 , Ensieh Salehghamari 1 , Khosro Khajeh 2 , Mahbube Kabiri 1 and Saied Naddaf 3 1 Extremophiles Lab., Dept. of Microbiology, Faculty of Biology, College of Science, University of Tehran, Tehran, Iran 2 Department of Biochemistry, Faculty of Science, Tarbiat Modarres University, Tehran, Iran 3 Parasitology department, Pasteur Institute of Iran, Teheran, Iran Fifty strains of moderately halophilic bacteria were isolated from various salty environments in Iran. A strain designated as SA-2 was shown to be the best producer of extracellular lipase and was selected for further studies. Biochemical and physiological characterization along with 16S rDNA sequence analysis placed SA-2 in the genus Salinivibrio. The optimum salt, pH, temperature and aeration for enzyme production were 0.1 M KCl, pH 8, 35 °C and 150 rpm, respectively. The enzyme production was synchronized bacterial growth and reached a maximum level during the early-stationary phase in the basal medium containing 1 M NaCl. Triacylglycerols enhanced lipase production, while carbohydrates had inhibitory effects on it. The maximum lipase activity was obtained at pH 7.5, 50 °C and CaCl 2 concentration of 0.01 M. The enzyme was stable at pH range of 7.5 – 8 and retained 90% of its activity at 80 °C for 30 min. Different concentrations of NaNO 3 , Na 2 SO 4 , KCl and NaCl had no affect on lipase stability for 3 h. These results suggest that the lipase secreted by Salinivibrio sp. strain SA-2 is industrially important from the perspective of its tolerance to a broad temperature range, its moderate thermoactiviy and its high tolerance to a wide range of salt concentrations (0 – 3 M NaCl). Keywords: Halophilic bacteria / Lipase activity / Lipase production / Salinivibrio / Thermohalophilic enzyme Received: November 05, 2007; accepted: January 09, 2008 DOI 10.1002/jobm.200700361 Introduction * Lipases are among the most important hydrolytic en- zymes with potential applications in a variety of bio- technological fields such as food, dairy, detergent pharmaceutical, agrochemical and oleochemical indus- tries. Many microbial lipases are available now and some of them have already been used in various indus- tries. However, they are not sufficient to meet most of the industrial demands. Since industrial processes are commonly carried out under harsh conditions, it would be of great importance to produce types of enzymes Correspondence: M. A. Amoozegar, Extremophiles Lab., Dept. of Micro- biology, Faculty of Biology, College of Science, University of Tehran, P.O. Box 14155-6455, Tehran, Iran E-mail: amozegar@khayam.ut.ac.ir Phone: +98-21-61112622 Fax: +98-21-66492992 which retain their optimal activity at extremes of pH, temperature and different concentrations of salts. Moderately halophilic bacteria are extremophiles mi- croorganisms which have adapted to live in a wide range of NaCl (1 – 25%) and constitute an interesting group of microorganisms that could be used as a source of such enzymes [1]. These organisms produce halotol- erant enzymes which are able to tolerate high ionic strength (up to 4 M NaCl) in their environments and in contrast to their extremely halophilic counterparts can be active in the absence of salts. Recently, a consider- able attention has been given to the enzymes produced by moderately halophilic microorganisms and their biotechnological potentials [2]. While there are numer- ous reports on the lipase production and characteriza- tion from non-halophilic microorganisms, very limited information is available on lipases from halophilic spe-