INTRODUCTION Historically, olive leaf extract has been widely used in folk medicine for combating fevers and other diseases, such as malaria (Benavente-Garcia et al., 2000). Olive leaf extract has the capacity to lower blood pressure in animals (Khayyal et al., 2002) and increases blood flow in coronary arteries, relieves arrhythmia and prevents intestinal muscle spasms (Zarzuelo, 1991). In addition, olive leaf extract and its phe- nolic compounds such as oleuropein, tyrosol, hydroxyty- rosol, caffeic acid, gallic acid and luteolin have antimicrobial activity against viruses, retroviruses, bacteria, yeasts, fungi, molds, and other parasites (Juven et al., 1968, Fleming et al., 1973; Mahjoub and Bullerman, 1987; Gourama et al., 1989; Tranter et al., 1993; Tassou and Nychas, 1995; Bisig- nano et al., 1999; McDonald et al., 2001; Tuck and Hayball, 2002; Korukluoglu et al., 2004; Micol et al., 2005). Pheno- lic compounds isolated from olive fruit have been shown to inhibit the growth of Escherichia coli, Klebsiella pneumoni- ae and Staphylococcus aureus (Aziz et al., 1998, Yigit et al., 2001). Gourama and Bullerman (1987) tested the effect of oleuropein on growth and aflatoxin production by Aspergillus parasiticus, and found that oleuropein stimulated mold growth but inhibited the production of aflatoxins. Markin et al. (2003) tested water extract of olive leaf against some microorganisms and found that Candida albicans was killed within 24 h. Sousa et al. (2006) reported that the determi- nation of phenolic compounds in ‘alcaparra’ table olives and the evaluation of their extract in vitro activity against Gram positive, Gram negative bacteria and fungi (Candida albicans and Cryptococcus neoformans). Some aldehydes obtained from olive fruit revealed antifungal activity against Trico- phyton mentagrophytes, Microsporum canis and Candida spp. (Battinelli et al., 2006). Many of the problems caused by yeasts results from the much higher attention paid to bacteria and moulds, which are more significant in terms of public health. Yeasts play a central role in the spoilage of foods and beverages, mainly those with high acidity and reduced water activity (a w ) (Loureiro and Queroly, 1999; Loureiro and Malfeito-Ferreira, 2003; Evans et al., 2004). Ismail et al. (2000) reported that Kloeckera apiculata, Saccharomyces cerevisiae, Schizosaccharomyces pombe and Candida spp. are respon- sible for the spoilage of foods that have been processed and packaged according to the normal standards of good man- ufacturing practice. In addition, yeasts are used during bio- logical control following harvest (Candida oleophila, Metschnikowia fructicola, etc.). The objectives of this study were (i) to investigate anti- fungal activity of extracts from olive leaf, which has been utilised as traditional folk medicine, and (ii) to evaluate the potential usage of olive leaf extract as natural preservative. MATERIALS AND METHODS Microorganism strains. Schizosaccharomyces pombe and Saccharomyces uvarum were obtained from Department of Food Engineering; Metschnikowia fructicola, Candida oleophi- la and Kloeckera apiculata were obtained from Department Annals of Microbiology, 56 (4) 359-362 (2006) Antifungal activity of olive leaf (Olea Europaea L.) extracts from the Trilye Region of Turkey Mihriban KORUKLUOGLU 1 *, Yasemin SAHAN 1 , Aycan YIGIT 1 , Reyhan KARAKAS 2 1 Department of Food Engineering, Faculty of Agriculture, Uludag University, Bursa, Turkey; 2 Susurluk College, BalIkesir University, Susurluk, BalIkesir, Turkey Received 29 June 2006 / Accepted 2 october 2006 Abstract - Antimicrobial properties of olive leaf extract on some yeast were examined in this study. Fresh olive leaf extracts were pre- pared using various solvents (water, ethanol, acetone, ethyl acetate) in Soxhlet apparatus. Antimicrobial effects of these extracts were tested against Saccharomyces cerevisiae ATCC 9763, Schizosaccharomyces pombe, Saccharomyces uvarum, Candida oleophila, Metschnikowia fructicola and Kloeckera apiculata. The antifungal activities of these extracts were tested by the disc diffusion assay, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). All extracts showed various degrees of antifun- gal effects with 10-28 µg/ml MIC, 20-48 µg/ml MFC and 1.5-9.3 mm inhibitory zone values against yeasts utilised, except water. The results indicated that the tested yeasts were sensitive to acetone and ethyl acetate extracts. It was determined that Saccharomyces cerevisiae ATCC 9763 was the most resistant among the yeasts. Key words: Olea europaea L., antifungal, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). * Corresponding author. Phone: +90-224-4428970; Fax: +90-224-4428077, E-mail: mihriban@uludag.edu.tr