RAPID METHOD FOR SCREENING THE TOLERANCE OF YEASTS TO ZINC (II) AND CHROMIUM (III) |
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Authors: | MARTIN BATI ,DARJA LENAR I ,JANEZ TUPAR,PETER RASPOR |
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Affiliation: | Biotechnology Department Mlinotest d.d., Food Industry Tovarnîska 14, 5 270 Adjo&všcina, SLOVENIA;Food Science and Technology Department Biotechnical Faculty, Chair of Biotechnology University of Ljublijana Jamnikarjeva 101, 1 1000 Ljubljana, SLOVENIA;Jožef Štefan Institute Jamova 39, 61 111 Ljubljana, SLOVENIA |
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Abstract: | Rapid screening of the tolerance of yeasts to zinc (II) and chromium (III) was performed by an agar diffusion test. A rapid and reliable procedure for the determination of metal ion concentration gradients on agar plates was developed. Different species of yeasts from the following genera were investigated: Arthroascus, Bulera, Dekkera, Debaryomyces, Dipodascopsis, Eremothecium, Candida, Hansenula, Kluyveromyces, Hormoacus, Geotrichum, Lipomyces, Pachysolen, Pichia, Saccharomyces, Schizosaccharomyces, Schizoblastosporion, Schwan-niomyces, Sporobolomyces, Yarrowia, Torulaspora, Zygosaccharomyces and Williopsis. The experimental conditions were defined as a constant volume of malt agar 32 cm3, and a temperature of 29C. After periods of 24, 47 and 72 h, the concentration intervals of growth inhibition were determined, and the yeasts investigated were grouped in different classes according to their tolerance to Zn (II) and Cr (III). Yeasts were found to be tolerant to significantly higher zinc (II) concentrations in the malt agar medium (5.9 mM to 20 mM) in comparison to chromium (III) (1.5 mM to 6.9 mM). Yeasts showed inter- and intra-generic differences in zinc (II) and chromium (III) tolerance. |
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