This strain exhibits interesting pleomorphic properties (Tareb et al. 2013) commercialized by Dupont–Danisco for animal nutrition as a feed additive for piglets (European Commission 2008). Lactobacillus farciminis CNCM-I-3699 is a probiotic strain (Bernardeau, Vernoux and Gueguen 2001a, b Bernardeau et al., 2009 Tareb et al. The FTIR analysis is efficient to separate and give data on mainly surface component differences observed previously between S colony morphotype (ropy and exopolysaccharide positive) and the R colony morphotype (non-ropy but highly autoaggregative).įTIR spectroscopy, Lactobacillus, polysaccharide, protein, pleomorphism INTRODUCTION Compared to S, the morphotype R exhibits a 1.27-fold higher signal at the wavenumber of 1637 cm −1 assigned to the amide I β-sheet and a 2.71-fold higher signal at the wavenumber of 1513 cm −1 assigned to the tyrosine involved in the β-sheet arrangement of proteins. 5.24% at 1068 cm −1) and capsular polysaccharides (16% vs. Significant increases in favor of morphotype S compared to R at specific wavenumbers for polysaccharides (22.18% vs. Based on spectral information in these two spectral ranges, clustering resulted in a dendrogram that showed a clear discrimination between both morphotypes. The main differences observed were localized in the polysaccharide (1200–900 cm −1) and protein (1700–1500 cm −1) regions. In this study, the potential of Fourier transform infrared (FTIR) spectroscopy for assessing putative biochemical and structural differences between the two variants, rough (R) and smooth (S), of Lactobacillus farciminis CNCM-I-3699, a pleomorphic strain, was investigated.