title: Quantification of micro-organisms in binary mixed populations by Fourier transform infrared (FT-IR) spectroscopy.
abstract: Fourier Transform Infrared (FT-IR) spectroscopy was used for the first time to determine the ratios of different microorganisms in mixtures. Exemplarily, systems composed of two food-associated yeast species (Saccharomyces cerevisiae/Hanseniaspora uvarum) and two yoghurt lactic acid bacteria (Lactobacillus acidophilus/Streptococcus salivarius ssp. thermophilus) were investigated. Determination of the cell number ratio in the lactic acid bacteria system was possible with a minimal prediction accuracy of +/- 16 ratio percentage points while the minimum accuracy of prediction in the yeast two-component system was +/- 4% (both at a 95% confidence level). These results show that FT-IR spectroscopy is potentially a rapid method for the quantification of cell ratios in mixtures of two different microorganisms, provided that the cell ratio does not drop below a certain, system-specific threshold.
authors.affiliation: Institut für Mikrobiologie, Forschungszentrum für Milch und Lebensmittel Weihenstephan, Technische Universität München, Freising, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Oberreuter
authors.forename: F
authors.initials: F
authors.lastname: Mertens
authors.forename: H
authors.initials: H
authors.lastname: Seiler
authors.forename: S
authors.initials: S
authors.lastname: Scherer
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000302:isolation & purification; D015169:Colony Count, Microbial / Q000379:methods; D007779:Lactobacillus acidophilus / Q000737:chemistry; D016018:Least-Squares Analysis; D011237:Predictive Value of Tests; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D013045:Species Specificity; D017550:Spectroscopy, Fourier Transform Infrared; D013291:Streptococcus / Q000737:chemistry; D015003:Yeasts / Q000737:chemistry* / Q000302:isolation & purification