Structural characterization and antioxidant potential of a novel anionic exopolysaccharide produced by marine Microbacterium aurantiacum FSW-25

An exopolysaccharide (EPS) producing strain FSW-25 was isolated from the Rasthakaadu beach Kanyakumari, Tamil Nadu India. Based on polyphasic taxonomy, the strain FSW-25 was assigned to the genus Microbacterium and found to be the closest relative of the species aurantiacum. Large quantity of EPS (7.81 g/l) was secreted by the strain upon fermentation using Reasoner's 2A medium enriched with 2.5% glucose and was designated as Mi-25. FT-IR spectrum revealed presence of hydroxyl, carbonyl, carboxyl, methyl and sulfate functional groups in purified EPS. The EPS Mi-25 has a molecular weight of 7.0 × 106 Da and mainly comprises of glucuronic acid followed by glucose, mannose and fucose. Rheological study revealed that Mi-25 possesses significant viscosity with pseudoplastic nature. Interestingly, it was observed that the EPS Mi-25 has higher antioxidant activity as compared to xanthan. The characteristics of EPS Mi-25 suggested that, it can be used as a potential antioxidant with viscosifier properties in diverse industrial sectors.