NIR TECHNIQUES IN YEAST IDENTIFICATION

The suitability of near infrared reflectance spectroscopy (NIR) for th e rapid identification of different yeasts was tested. Yeasts were gro wn in batch culture and samples were taken from the exponential and st ationary growth stages; later samples were divided into aliquots, one of which was heat-shocked. The four yeasts tested were morphologically different. Optimal growth temperatures were all in the range of 30-35 degrees C and at 30 degrees C growth rates of mixed cultures did not differ significantly from those of monocultures. NIR spectra of the st rains investigated were significantly different. The growth stage or h eat-shock treatment had significant effects on the spectrum. Mixtures of two pure cultures (0, 10, 20 ... 90% ''infection'') had NIR spectra which were intermediate to those of the pure culture and even 10% con tamination caused a significant difference.