The structure of O-polysaccharide isolated from Cronobacter universalis NCTC 9529T

The O-polysaccharide (OPS) was isolated from Cronobacter universalis NCTC 9529T, a new species in the genus Cronobacter, which was created by the reclassification of the species Enterobacter sakazakii. Purified polysaccharide was analyzed by NMR spectroscopy (1H, COSY, TOCSY, ROESY, HSQC, and HSQC-TOCSY) and chemical methods. The monosaccharide derivatives were analyzed by gas chromatography, and gas chromatography-mass spectrometry. These experiments enabled the type and number of monosaccharides in the repeating unit of OPS, their positions of linkages, and absolute configuration to be determined. Together the chemical analysis established a structure of the OPS of C. universalis NCTC 9529T: →3)--L-FucpNAc-(1→4)--D-Manp-(1→3)--L-FucpNAc-(1→3)-β-D-GlcpNAc-(1→ [A, B, C, D] OPS isolated from C. universalis was structurally characterized for the first time

Structure of the iron-binding exopolysaccharide produced anaerobically by the Gram-negative bacterium Klebsiella oxytoca BAS-10.

Klebsiella oxytoca BAS-10 is a Gram-negative micro-organism capable of growing on high concentrations of heavy metals. This bacterium produces large amounts of an iron-binding exopolysaccharide that, in the presence of metallic cations, precipitates as a dense gel. The primary and secondary structure of the repeating unit of such polysaccharide has been characterised by chemical and spectroscopic methods, resulting in the following heptasaccharide: 2)-α-Rha-(1_3)- β-Gal-(1_2)-α-Rha-(1_4)-β-GlcA-[β-GlcA-(1_4)]-(1_3)-α- Rha-(1_3)-α-Rha-(1_. The absolute configurations for the Rha units are L, while those for the GlcA and Gal residues are D

Structure-activity relationship of the exopolysaccharide from a psychrophilic bacterium: A strategy for cryoprotection

Microrganisms from sea ice, glacial and subglacial environments are currently under investigation due to their relevant ecological functions in these habitats, and to their potential biotechnological applications. The cold-adapted Colwellia psychrerythraea 34H produces extracellular polysaccharides with cryoprotection activity. We here describe the purification and detailed molecular primary and secondary structure of the exopolysaccharide (EPS) secreted by C. psychrerythraea 34H cells grown at 4 °C. The structure was determined by chemical analysis and NMR. The trisaccharide repeating unit of the EPS is constituted by a N-acetyl quinovosamine unit and two residues of galacturonic acid both decorated with alanine. In addition, the EPS was tested in vitro showing a significant inhibitory effect on ice recrystallization. In-depth NMR and computational analysis suggest a pseudohelicoidal structure which seems to prevent the local tetrahedral order of the water molecules in the first hydration shell, and could be responsible of the inhibition of ice recrystallization. As cell cryopreservation is an essential tool in modern biotechnology and medicine, the observations reported in this paper could pave the way for a biotechnological application of Colwellia EPS