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Exopolysaccharide Production from Marine Bacteria and Its Applications
Published in Se-Kwon Kim, Marine Biochemistry, 2023
Prashakha J. Shukla, Shivang B. Vhora, Ankita G. Murnal, Unnati B. Yagnik, Maheshwari Patadiya
Dextran and levan are extracellularly synthesized polysaccharides. The synthesis of dextran, levan and their derivatives is directly induced in the presence of sucrose (Schmid et al., 2015). The most common sucrase activity–based polymer is dextran, which mainly consists of α-(1–6) linked glucose. Dextran-based polymer is released outside the cell by the dextransucrase, the key enzyme for dextran synthesis (Schmid et al., 2015). Levan, which is produced by levansucrases, can also act as fructose transferases producing polyfructan (levan). Table 18.1 shows various bacterial EPSs, their sugar components and the transport mechanism.
Molecular Aspects of Anti-Polysaccharide Antibody Responses
Published in Maurizio Zanetti, J. Donald Capra, The Antibodies, 2002
Kurt Brorson, Pablo Garcia-Ojeda, Kathryn E. Stein
Levans are neutral polymers of fructose joined by either (3(2 : 6) or (3(2 : 1) linkages. Plant levans, made for energy storage, are linear polymers with either predominantly p(2 : 6) linkages (monocotyledons, e.g., rye grass) or predominantly (3(2 : 1) linkages, also known as inulin (dicotyledons, e.g., Jerusalem artichokes; [50]). Bacterial levans (BL) are extra-cellular products of microbial fermentation by Bacillus and Erwinia sp. bacteria which synthesize levan from sucrose and secrete it [51]. BL is much larger (Mr 106 Daltons) than plant levans, is readily soluble in water, and consists of a backbone of (3(2: 6) linked fructose with branches of (3(2 : 1)-linked fructose.
Gut Bacteroides species in health and disease
Published in Gut Microbes, 2021
The OMVs of Bth contain glycosyl hydrolases that help in the degradation of levan, a common non-structural carbohydrate in plants. The by-products of levan degradation include extracellular fructo-oligosaccharides that are important for the growth of other Bacteroides spp.33–35 Another example of OMV-associated intra-genus support involves Bacteroides ovatus and Bacteroides vulgatus. The glycosyl hydrolases in the OMVs of B. ovatus break down inulin, the products of which are utilized by B. vulgatus.36 Thus, the genus Bacteroides is an efficient public goods provider, and its services generally support other species in the microbial gut community.
Biofilm-based delivery approaches and specific enrichment strategies of probiotics in the human gut
Published in Gut Microbes, 2022
Jie Gao, Faizan Ahmed Sadiq, Yixin Zheng, Jinrong Zhao, Guoqing He, Yaxin Sang
Prebiotics containing levan can be specifically utilized by Bacteroides thetaiotaomicron.147 Similarly, yeast mannan (indigestible water-soluble polysaccharide) has been reported to specifically promote the growth of B. thetaiotaomicron and B. ovatus in trials based on human colonic microbiota model.148 Soluble dietary fiber (10% inulin) reportedly enhances growth and abundance of Bacteroides fragilis with a concomitant increase in IgA.149