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

摘要

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.