Biosynthesis, purification and structure-property relationships of new cyanobacterial exopolysaccharides

Exopolysaccharides are considered as omnipresent and abundant bioproducts. However, the diversity of cyanobacteria offers a great opportunity for discovering new bioproducts as they are not properly explored. The current work targeted to characterize an indigenous cyanobacterial strain CCC-746 isolated from Bishnupur, India for production of exo-polysaccharides. The molecular and microscopic observation stated that the isolated cyanobacteria is Anabaena sp. The analysis of biomass composition showed carbohydrates, protein, lipid, ash and moisture content are 32.10%, 36.56%, 24.13%, 5.89% and 1.32% (w/w) respectively. The maximum production of EPS was 340.70 mg/L, when grown in 10 mM CaCl2 supplemented BG11 medium. The capsular polysaccharide and released exo-polysaccharide were purified by gel filtration chromatography, and molecular weight was found as 12.52 and 9.2 kDa, respectively. The major component of both exo-polysaccharides was carbohydrate with glucose, xylose and glucuronic acid as major monosaccharides. Capsular polysaccharide and released exo-polysaccharide were composed of [→4)-Glcp-(1→] backbone. Both exo-polysaccharide were found negative in charge and showed remarkable antioxidant and scavenging activities. Capsular polysaccharide and released exo-polysaccharide solubilized in aqueous solution exhibited the behaviour of pseudo-plastic fluids. •Novel indigenous strain of Anabaena sp. has shown to accumulate EPS.•Over 340.7 mg/L of EPS has been obtained when exposed to CaCl2.•Yield of CPS-74.52% & RPS-82.62% was obtained after extraction.•Analysis showed increased concentration of glucose, xylose and glucuronic acid.