<title>Characterization of biotechnologically and medically relevant yeasts (fungi) by Fourier transform infrared spectroscopy</title>

Abstract

Institute of Biotechnology, Permoserstrae 15, 0-7050 Leipzig Robert Koch-Insitute of the Federal Health Office of Germany, Nordufer 20, W-l000 Berlin 65 1. ABSTRACTThe Fourier-Transform infrared spectra of intact procaryotic cells (bacteria) have already been used in the past to characterize (differentite, classify and identify) a variety of bacterial strains and taxa In this paper the essential features of a methodology are described which extend the FT-IR pattern recognition approach to intact eucaryotic cells (yeasts/fungi) . Basically, the characteristic information pertaining to microbial FT-IR patterns is explored by applying multivariate statistics and cluster analysis to both, the time and frequency domain of the mid-ir spectral data. MATERIALS, METHODS AND RESULTSFT-IR spectra have been recorded on an IFS-48 spectrometer (Bruker, Analytische Metechnik, Karlsruhe) . The digital spectra were transferred to a MicroVAX workstation 2000 (Digital Equipment) for further evaluation. Prior to all IR measurements a standard experimental procedure concerning culture media, cultivation time, harvesting, sample preparation (here as KBr pellets) and spectral parameters was applied.The discrimination of microorganisms was attained via comparison of FT-IR data either in the time or the frequency domain. The "reproducibility level" ot repetitive and independent measurements of seven different strains over a period of six months gave similarity ratios of approximatly 98% (Fig. 1) . Different yeast species of the genus Rhodotorula, Kluyveromyces, Hansenula and Candida were classified on the basis of IR-data in the time domain according to classical taxonomic schemes: Rhodotorula, Kluyveromyces and Hansenula are grouped into dense clusters. The genus Candida proved to be a heter%genous group as already described by conventional taxonomic techniques Grouping of different strains of the genus Rhodotorula and Saccharomyces in the frequency domain using only the first 64 Fourier coeff icients is shown in Fig. 2. Classification of 108 yeast strains by a linear discriminance analysis with non-elementary d'iscriminance coefficients on the basis of the first 46 elements of the FT-IR patterns yielded to a resubstitution rate of 92%, i.e. 92% of the strains wee correctly grouped in agreement with conventional taxonomic schemes O-8194-0706-2/92/$4.oo Si°/E Vol. 1575 8th International Conference on Fourier Transform Spectroscopy(1991) / 441 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 08/01/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx