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An exopolysaccharide obtained from an alkaliphilic bacterium closely related to Bacillus spp. was found to contain D-galactopyranuronic acid (GalpA), 2,4-diacetamido-2,4,6-trideoxy-D-glucopyranose (QuipNAc4NAc), 2-acetamido-2-deoxy D-mannopyranuronic acid (ManpNAcA) and one uncommon unit of D-galactopyranuronic acid with the carboxyl group amide-linked to glycine [GalpA(Gly)]. The polysaccharide was studied by one-dimensional and two-dimensional 1H NMR and 13C NMR spectroscopy both on native polysaccharide and on monosaccharides and oligosaccharides obtained from methanolysis and from anhydrous HF solvolysis. The following linear structure of the repeating unit was established: →3)-α-D-GalpA(Gly)-(1→4)-β-D-ManpNAcA-(1→4)-α-D-GalpA-(1→3)-α-D-QuipNAc4NAc-(1→. A preliminary phylogenetic assignment for the bacterium is also reported.

structure, determination, bacteria, exopolysaccharide, glycine, Bacillus, phylogenetic analysis, Structure determination, alkaliphilic

NCBI PubMed ID: 10491103
Journal NLM ID: 0107600
Publisher: Oxford, UK: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Correspondence: parrilli@unina.it
Institutions: Dipartimento di Chimica Organica e Biologica, Universita di Napoli Federico II, Italy, Department of Microbiology and Immunology, University of Leicester, UK
Methods: NMR-2D, FAB-MS, NMR, HF solvolysis, Smith degradation, MALDI-MS, methanolysis

Numerous microorganisms inhabiting harsh niches produce exopolysaccharides as a significant strategy to survive in extreme conditions. The exopolysaccharides synthesized by extremophiles possess distinctive characteristics due to the varied harsh environments which stimulate the microorganisms to produce these biopolymers. Despite many bioprocesses have been designed to yield exopolysaccharides, the production of exopolysaccharides by extremophiles is inefficient compared with mesophilic and neutrophilic exopolysaccharide producers. Meanwhile, the industrial development of novel extremophilic exopolysaccharides remains constrained due to the lack of exploration. In this review, we summarize the structure and properties of various exopolysaccharides produced by extremophiles, and also discuss potential metabolic and genetic engineering strategies for enhanced yield and modified structure of extremophilic exopolysaccharides. Special focus is given to the applications of extremophilic exopolysaccharides in the areas of biomedicine, food industry, and biomaterials via nano-techniques, casting and electrospinning.

exopolysaccharide, Extremophile, Exopolysaccharide Biosynthesis, Exopolysaccharide application, Exopolysaccharide property

NCBI PubMed ID: 30446151
Publication DOI: 10.1016/j.carbpol.2018.10.011
Journal NLM ID: 8307156
Publisher: Elsevier
Correspondence: David.Salem@sdsmt.edu; Rajesh.Sani@sdsmt.edu
Institutions: Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA, BuG ReMeDEE consortium, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA, Department of Materials and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA, Composite and Nanocomposite Advanced Manufacturing - Biomaterials Center (CNAM-Bio Center), Rapid City, SD 57701, USA

Bacterial extracellular polysaccharides are known as a cell-bound capsule, a sheath, or a slime, which is excreted into the environment. They play an important role in virulence of medical bacteria and plant-to-symbiont interaction and are used for serotyping of bacteria and production of vaccines. Some exopolysaccharides have commercial applications in industry, and claims of health benefits have been documented for an increasing number of them. Exopolysaccharides have diverse composition and structure, and some contain sugar and non-sugar components that are found in bacterial carbohydrates only. The present article provides an updated collection of the data on exopolysaccharides of various classes of gram-negative and gram-positive bacteria reported until the end of 2019. When known, biosynthesis pathways of exopolysaccharides are treated in a summary manner. References are made to structure and biosynthesis relatedness between exopolysaccharides of different bacterial taxa as well as between bacterial polysaccharides and mammalian glycosaminoglycans.

polysaccharide structure, Gram-negative bacteria, capsule, Biofilm, polysaccharide biosynthesis, gram-positive bacteria, Monosaccharide composition, Bacterial exopolysaccharide, non-sugar component

Publication DOI: 10.1016/B978-0-12-819475-1.00005-5
Publisher: Elsevier
Correspondence: marie-rose.vancalsteren@canada.ca; yknirel@gmail.com
Editors: Barchi J, Kamerling H
Institutions: N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, Saint-Hyacinthe Research and Development Centre, Agriculture and Agri-Food Canada, Saint-Hyacinthe, QC, Canada

structure, determination, bacteria, exopolysaccharide, glycine, Bacillus, phylogenetic analysis, Structure determination, alkaliphilic