Production and applications of microbial exopolysaccharides CH,OH CH2OH CH,OH b)βDgu(1→3)-BDu(1→3)-Dgu(1→3)阝-Dgu B-D-glu OOOooO6 ooooooooooo。 igure 7. 2 Three main types of homopolysaccharide. a) Single linkage type, eg curdlan. b) Side chain type, eg scleroglycan. c)Branched chain type, eg dextran. The figure also show various ways of illustrating exopolysaccharide structure 7.3.2 Heteropolysaccharides repeat units Microbial heteropolysaccharides are almost entirely all composed of repeating units of between two and eight monosaccharides. The units often contain D-glucuronicacid and short side-chains of one to four residues are com everal different side-chains are found in some heteropolysaccharides. The structure of xanthan illustrates these points and is shown in Figure 7.3. A few bacterial alginates are exceptionsProduction and applications of microbial exopolysaccharides 199 Figure 7.2 Three main types of hornopolysaccharides. a) Single linkage type, eg curdJan. b) Side chain type, eg scleroglycan. c) Branched chain type, eg dextran. The figure also show various ways of illustrating exopolysaccharide structure. 7.3.2 Heteropolysaccharides Microbial heteropolysaccharides are almost entirely all composed of repeating units of between two and eight monosaccharides. The units often contain D-glucuronic acid and short sidechains of one to four residues are common. Several different sidechains are found in some heternplysaccharide. The structure of xanthan illustrates these points and is shown in Figure 7.3. A few bacterid alginates are exceptions. repeat units