Properties of a glycogen like polysaccharide produced by a mutant of Escherichia coli lacking glycogen synthase and maltodextrin phosphorylase. (20th January 2016)

• Record Type: Journal Article
• Authors: Kwak, Ji-Yun; Kim, Min-Gyu; Kim, Young-Wan; Ban, Hyun-Seung; Won, Mi-Sun; Park, Jong-Tae; Park, Kwan-Hwa
• Is Part Of: Carbohydrate polymers. Volume 136(2016)
• Page Start: 649
• Page End: 655
• Publication Date: 2016-01-20
• Subjects: Escherichia coli mutant -- Intracellular polysaccharide -- Glycogen -- Amylase -- Digestibility kinetics -- Water solubility -- Immunostimulating effect; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2015.09.091
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Characteristics of 3 polysaccharides (PSs) from a Escherichia coli mutant were analyzed. The PSs had smaller molecular weights and shorter side chains than glycogens. Maximal water-solubility of the PSs was 230 mg/mL at room temperature. In hydrolysis experiment with amylases, the PSs had greatly reduced digestibility in comparison to amylopectin. The PSs exhibited immunostimulating effect on mouse macrophage cell. Abstract: Escherichia coli mutant TBP38 lacks glycogen synthase (GlgA) and maltodextrin phosphorylase (MalP). When grown on maltose in fed-batch fermentation TBP38 accumulated more than 50-fold higher glycogen-type polysaccharide than its parental strain. The polysaccharides were extracted at different growth stages and migrated as one peak in size-exclusion chromatography. TBP38 produced polysaccharides ranging 2.6 × 10 6 –4.6 × 10 6 Da. A ratio of short side-chains (DP ≦ 12) in the polysaccharides was greater than 50%, and number-average degree of polymerization varied from 9.8 to 8.4. The polysaccharides showed 70–290 times greater water-solubility than amylopectin. K m values using porcine and human pancreatic α-amylases with polysaccharides were 2- to 4-fold larger than that of amylopectin. k cat values were similar for both α-amylases. The TBP38 polysaccharides had 40–60% lower digestibility to amyloglucosidase than amylopectin. Intriguingly, the polysaccharides showed strong immunostimulating effects on mouse macrophage cell comparable to lipopolysaccharides. The lipopolysaccharide contamination levels were too low to account for this effect.