Multivariate statistical methods for discrimination of lactobacilli based on their FTIR spectra

Abstract

-In this study, 41 strains belonging to 6 Lactobacillus species originating from culture collections, and isolates from homemade cheese that had previously been genetically classified, were discriminated based on their FTIR spectra. The lactobacilli species L. brevis, L. diolivorans, L. plantarum and L. rhamnosus could be differentiated on the basis of their FTIR spectra by applying multivariate statistical techniques (Hierarchical Cluster Analysis, Principal Component Analysis and Multidimensional Scaling). The strains belonging to L. paracasei and L. casei could not be separated from each other, and formed one group that was distanced from the other investigated species. The combination of common multivariate statistical methods used for the analysis of FTIR spectra could provide a powerful method for discrimination and even the identification of lactobacilli on a species level. The strains and subspecies within the lactobacilli species could not be differentiated by applying multivariate exploratory statistical methods. The FTIR spectra of lactobacilli were robust against the variation in the consistency of the growth medium (broth or agar medium of the same composition), applied spectroscopic techniques (KRS-5 or tablets) and the recorded biomass quantities of 2 and 3 mg. Furthermore, the distances between the two spectra of the same selected strain, which were sampled ca. 12 months apart, were insignificant. lactobacilli / FTIR spectroscopy / multivariate statistical methods multidimensionnelles, couramment utilisées pour l'analyse de spectres IRTF, peut fournir une méthode puissante pour la discrimination et même l'identification de lactobacilles à l'échelle de l'espèce. Les souches et sous-espèces parmi les espèces de lactobacilles ne peuvent pas être différenciées en appliquant des méthodes statistiques multidimensionnelles exploratoires. Les spectres IRTF des lactobacilles sont robustes quels que soient les changements de consistance des milieux de culture (milieu liquide ou gélosé de la même composition), les méthodes spectroscopiques appliquées (KRS-5 ou comprimé) ou la quantité de biomasse analysée (2 ou 3 mg). De plus, la distance entre deux spectres d'une même souche sélectionnée, échantillonnée avec 12 mois d'écart, est insignifiante.lactobacilles / spectroscopie IRTF / méthodes statistiques multidimensionnelles

Applications of Infrared and Raman Spectroscopies to Probiotic Investigation

“…Several authors contributed for the creation of spectral libraries of different species of the genera Lacbobacillus , Lactococcus , Leuconostoc , Streptococcus , Pediococcus , Propionibacterium and Enterococcus [32,40,41,42,43,44,45,46,47]. FTIR based techniques enabled the accurate identification of different lactic acid bacteria and probiotics isolated from rumen extracts [48], human feces [49] and food matrices like breweries [50], cheese and dairy products [51,52,53,54,55,56,57,58], water kefir [59], pickled and fermented vegetables food and juice, and salami [44,47], meat [60]. …”

Effect of drying methods of microencapsulated Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris on secondary protein structure and glass transition temperature as studied by Fourier transform infrared and differential scanning calorimetry

“…Fourier transform infrared bands were used to classify 41 strains of 6 lactobacilli isolated from cheese using the hierarchical cluster analysis method (Savic et al, 2008). More specifically, the use of cluster analysis has been developed to categorize characteristics of the lactobacilli S-layer (Mobili et al, 2009).…”

Rapid tool for identification of bacterial strains using Fourier transform infrared spectroscopy on genomic DNA

“…Because this method is cost-effective, rapid and simple, FT-IR spectroscopy has been successfully applied in the identification of various bacteria at the species and strain levels (Ngo-Thi et al 2003;Naumann et al 2005;Fischer et al 2006), including for classification of Bacillus (Beattie et al 1998;Mietke et al 2010) and Lactobacillus strains Mariey et al 2001;Wenning et al 2010;Mouwen et al 2011). Furthermore, lactic acid bacteria were characterized by FT-IR spectroscopy combined with multivariate statistical methods from several food products including milk (Weinrichter et al 2001), cheese (Amiel et al 2000;Oust et al 2004;Savi c et al 2008) and meat products (Oust et al 2004). However, the reproducibility of whole-cell FT-IR has been limited by the culture conditions of the micro-organism.…”