Potentiality of Fourier Transform Infrared Spectroscopy (FTIR) for discrimination and identification of dairy Lactic acid bacteria

The potentiality of FTIR spectroscopy for the identification of lactic acid bacteria (LAB) used in the dairy industry was tested. For this purpose, spectra of different strains were recorded using standardized conditions. These strains were species of Lactobacillus (12 species, 3 sub- species), Lactococcus (4 species, 3 subspecies), Leuconostoc (3 species, 3 subspecies), Weissella (1 species) and Streptococcus (2 species) involved in the soft cheese industry . Spectral libraries were then established by statistical analysis. Reference strains were then tested on these libraries, and 100% of correct identifications were obtained at the genus and species level, 86% at the subspecies level. Well-identified strains were included in libraries. Wild isolates ( n = 48) previously identified by biochemical tests and RAPD method were then tested. We obtained 100% at the genus level and 69% at the species level of correlation between FTIR and other methods. Finally, spectra of reference strains performed in other laboratories were tested with the same method, and the results tallied with official identification in 100% of the cases at the genus level and in 41% of the cases at the species level. These results concerning a few strains allow us to plan the development of a more complete database for rapid identification of LAB.