A NEW WAY OF IDENTIFICATION OF YEASTS: USE OF NIR TECHNIQUE

Abstract

Four strains of Saccharomyces genera were investigated: S. pastorianus CBS 1503, S. cerevisiae CBS 1395, S. cerevisiae CB 67 and S. cerevisiae CB 89. The aim of our work was to test the suitability of NIR technique for rapid identification of different yeasts. Yeasts were grown in batch culture and samples were taken from the exponential and stationary growth stages, later ones were divided into parts and one of them was heat-shocked. The four yeasts tested were morphologically different, the CBS signed showed oval, the CB signed ones had round shaped cells. Optimum growth temperatures were all in the range of 30-35 ⁰C, and at 30⁰C growth rates of mixed cultures did not differ significantly from those of monocultures. The SDS-PAGE protein prints of the four strains were different both in the number of subfractions apd their molecular mass distributions. This method is suitable to characterize and differentiate the investigated yeasts . Quantitative evaluation ofthe SDS-PAGE patterns enables us to detect infections in the pure culture . NIR spectra of the investigated strains were significantly different. The growth stage or heat-shock treatment had serious effect on the spectrum. Mixtures of two pure cultures (0, 10, 20 ... 90% 'infection') showed NIR spectra in between those of the pure culture and even 10% contamination caused a significant difference.