Statistical optimization, physio-chemical and bio-functional attributes of a novel exopolysaccharide from probiotic Streptomyces griseorubens GD5

In this study, we assessed the bio-functional attributes of an exopolysaccharide (EPS) produced by the actinobacterial probiont Streptomyces griseorubens GD5. The EPS production was doubled to 9.50 g/L by varying the concentration of media components using Response surface methodology. The physio-chemical properties of GD5EPS were examined by various analytical techniques. Several functional groups were detected in FT-IR spectra, including β-glycosidic linkages, hydroxyl, carboxyl, and amide groups. Glucose, galactose, and mannose were detected from NMR spectra whilst the occurrence of arabinose, glucose, galactose, mannose, and xylose, were detected from HPLC chromatogram, signifying that GD5EPS is heteropolysaccharide in nature. The thermogram profile and SEM-EDX spectra of the extracted EPS indicated that it was highly thermo-stable, compact and porous, with flake-like structural units with the elemental composition of C, O, P, Mg, K, Ca, and Na. The GD5EPS also revealed potential antioxidant, emulsifying and antibiofilm efficacies, which corroborated that EPS derived from S. griseorubens GD5 might be a promising food supplement.