Structural characterisation of the exopolysaccharide produced by Lactobacillus delbrückii subspecies bulgaricus rr grown in skimmed milk

Abstract

The exopolysaccharide of Lactobacillus delbrückii subsp. bulgaricus rr, isolated from skimmed milk, is a heteropolymer of D-galactopyranosyl, D-glucopyranosyl, and L-rhamnopyranosyl residues in the molar ratio 5:1:1. The structure was established by linkage analysis and 1D and 2D NMR spectroscopy of the native polysaccharide, in combination with characterisation of oligosaccharide fragments, obtained by Smith degradation and partial acid hydrolysis, using methylation analysis, EIMS, and 1D and 2D 1H NMR spectroscopy. The polysaccharide has a branched heptasaccharide repeating unit with the following structure: -->2)-[beta-D-Galp-(1-->3)]-alpha-D-Galp-(1-->3)- beta-D-Glcp-(1-->3)-[beta-D-Galp-(1-->4)]-beta-D-Galp-(1-->4)-[alpha-L- Rhap-(1-->3)]-alpha-D-Galp-(1-->.

Structure of the extracellular polysaccharide produced by Lactobacillus delbrueckii subsp. bulgaricus 291

“…The 1 J C-1,H-1 values of the anomeric 13 C atoms of residues A ( 1 J C-1,H-1 162 Hz), B ( 1 J C-1,H-1 161 Hz), C ( 1 J C-1,H-1 161 Hz), and D ( 1 J C-1,H-1 163 Hz) are in agreement with b anomeric configurations, and that of residue E ( 1 J C-1,H-1 173 Hz) with a anomeric configuration. 15 Combining the 13 C NMR data and the methylation analysis data of the EPS, taking into account published 13 The assignment of interresidual cross-peaks in the 2D NOESY spectrum (Fig. 7) and of long-range couplings in the HMBC spectrum (Fig.…”

“…2D NOESY experiments were performed with a mixing time of 200 ms and 2D off-resonance ROESY spectra were obtained with a mixing time of 300 ms; both NOESY and ROESY spectra were acquired with 512 experiments of 1024 points with 16-32 scans per increment. Both natural abundance 13 C-1 H 2D HMQC and 13 C-1 H 2D HMBC experiments were recorded without decoupling during acquisition of the 1 H FID. A total of 512 free induction decays of 1024 data points were acquired using 140 or 400 scans per decay.…”

“…bulgaricus characterized so far are mainly composed of Glc and Gal 9,10 or of Glc, Gal and Rha. [11][12][13] A detailed structural study has been performed on the EPS produced by Lb. delbrueckii subsp.…”

“…bulgaricus rr having a branched heptasaccharide repeating unit composed of Gal, Glc, and Rha in a molar ratio of 5:1:1. 13 structed skimmed milk containing 0.35% peptone and 0.35% yeast extract, was isolated by ethanol precipitation of the protein-free culture supernatant followed by gel-filtration using Sephacryl S-500. The purity of the EPS was confirmed by 1 H NMR spectroscopy (vide infra).…”

Locticacid bacteria: funcionality, polysaccharides, therapeutic potencial and applications in food

“…Se ha probado que sales de Mg , por ejemplo, infuye en la actividad de la enzima fosfoglucomutasa, que participa en la biosíntesis de EPS, catalizando la transferencia de grupos fosfato entre los carbono C1 y C6 de la glucosa [64]. Así, como el extracto hidrosoluble de soja, al ser un medio complejo, rico en aminoácidos, vitaminas y sales minerales (~216 mg/L de Mg Se han estudiado y usado por muchos investigadores diferentes técnicas para la determinación de EPS en las últimas dos décadas [24,9,23,22,81,37,65,66,7,20,112,25,34,35]. Todos estos métodos envuelven la combinación de técnicas para aislar, purifcar y cuantifcar los EPS en un medio de cultivo.…”