EXTRACELLULAR LIPOLYTIC ENZYME ACTIVITY OF A NEWLY ISOLATED DEBARYOMYCES HANSENII

Abstract

A strain isolated from waste of a milk products plant and exhibited extracellular lipolytic activity was identified as Debaryomyces hansenii by 5.8S rRNA and 28S rRNA gene sequence analyses. Lipolytic activity was assayed spectrophotometrically by using p-nitrophenylpalmitate. Higher specific lipolytic activities were obtained in the presence of tristearin (0.68 U/mg prot), oleic acid (0.56 U/mg prot), and soybean oil (0.36 U/mg prot) than other triglycerides, fatty acids, and vegetable oils considered as carbon sources. Cheese whey appeared to be a good alternative to lipidic substances for lipolytic activity. Among various organic and inorganic nitrogen sources, soy flour was found to attain the lipolytic activity similar to that provided by universal yeast medium components. This work is the first report on the discussion of lipolytic activity enhancement by D. hansenii through modulating the cultivation medium. It also proposes low cost medium nutrients that could be of industrial value and could serve as basal nutrients for further optimization studies on the lipase production by D. hansenii.

Keywords:

• Debaryomyces hansenii
• fatty acids
• lipase
• lipolytic activity
• vegetable oils

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support provided by Ankara University Biotechnology Institute (Project No: 2005-164 of the SPO Project No: 2001K120240) and by Ankara University Scientific Research Projects Unit (Project No: 2007-0745004-HPD). The suggestions and experimental support from Prof. Dr. G. Dönmez and S. Ertuğrul (Ankara University Department of Biology) on the isolation of microorganism are gratefully recognized. Sincere thanks are extended to Assoc. Prof. Dr. H. Özdağ and G. Özsöz (Ankara University Biotechnology Institute) for their technical and experimental assistances on gene sequence analyses, respectively. Fatty acid compositions of vegetable oils were kindly determined by Prof. Dr. A. Tekin (Ankara University Department of Food Engineering).