Rapid and Reliable Identification of Food-Borne Yeasts by Fourier-Transform Infrared Spectroscopy

Abstract

Computer-based Fourier-transform infrared spectroscopy (FT-IR) was used to identify food-borne, predominantly fermentative yeasts. Dried yeast suspensions provided the films suitable for FT-IR measurement. Informative windows in the spectrum were selected and combined to achieve optimal results. A reference spectrum library was assembled, based on 332 defined yeast strains from international yeast collections and our own isolates. All strains were identified with conventional methods using physiological and morphological characteristics. In order to assess identification quality, another 722 unknown yeast isolates not included in the reference spectrum library were identified both by classical methods and by comparison of their FT-IR spectra with those of the reference spectrum library. Ninety-seven and one-half percent of these isolates were identified correctly by FT-IR. Easy handling, rapid identification within 24 h when starting from a single colony, and a high differentiation capacity thus render FT-IR technology clearly superior to other routine methods for the identification of yeasts.

Sources of the adventitious microflora of a smear-ripened cheese

“…Fourier-transform infrared (FTIR) spectroscopy was performed to identify yeast isolates as described previously by Kümmerle et al (1998). For recording and evaluating the spectra, an IFS-28B FTIR spectrometer and the opus software for Windows, version 3.17 (Bruker, Ettlingen, Germany), were used.…”

FTIR spectroscopic analysis of Saccharomyces cerevisiae cell walls: study of an anomalous strain exhibiting a pink-colored cell phenotype

“…FTIR data from bacteria have also been correlated with modi¢cations in secondary structures and this in relation with a resistance phenotype [15,16]. Studies concerning yeasts have been reported, but only for classi¢cation purposes with a correct identi¢cation of 97.5% [17] or for the analysis of homopolymers extracted from cell walls [18]. To our knowledge, there is no FTIR report on S. cerevisiae cell wall, although recently a spectroscopic study, in conjunction with statistical methods, has been carried out on 1000 mutagenized £ax plants to monitor structural and architectural cell wall alterations [19].…”

Direct spectroscopic (FTIR) detection of intraspecific binary contaminations in yeast cultures

“…Fourier transform infrared spectroscopy (FTIR) has been introduced in microbiology for species identification and strain characterization Naumann et al, 1991;Goodacre et al, 1996;Kummerle et al, 1998;Oberreuter et al, 2002;Wenning et al, 2002;Lai et al, 2004;Zhao et al, 2004;Yu & Irudayaraj, 2005;Fischer et al, 2006;Al-Qadiri et al, 2008). The advantages of this technique, such as rapidity, low consumable cost and the possibility to process several samples simultaneously, suggested the extension to the characterization of binary mixtures of microorganisms belonging to two different species, while demonstrating a good level of linearity between contamination levels and the corresponding variations of the spectra (Oberreuter et al, 2000;Al-Qadiri et al, 2006;Wenning et al, 2006).…”