Journal of Material Sciences & Engineering

Gloeocapsa gelatinosa as a source of extracellular polymeric substances: production, structural characterization and antioxidant activity

Abstract

Wejdene Gongi, Nereida Cordeiro, Juan Luis Gomez Pinchetti and Hatem Ben Ouada

Cyanobacterial extracellular polymeric substances are polymeric materials that own characteristics suitable for industrial and biotechnological applications. The thermophilic cyanobacteria Gloeocapsa gelatinosa was cultivated in a cylindrical reactor and the production of biomass and EPSs were investigated during a 15 days period. The results revealed that this strain is amongst the most efficient EPSs producer (0.8 g L-1 in 12 days). EPSs produced were sulphated heteropolysaccharides composed by nine different monosaccharides and two uronic acids. Thermogravimetric analysis showed that EPSs were extremely thermostable and the atomic force microscopy analysis showed that they are formed by pointed structural. Beyond that, EPSs presented high levels for water holding capacity and water holding index. The EPSs display an effective antioxidant activity via directly scavenging free radicals, particularly DDPH when compared to L-ascorbic acid (IC50 of 0.2 and 0.6 g L-1, respectively) and as a metal chelating agent when compared to EDTA (0.6 and 0.8 g L-1, respectively). The results obtained stimulate the industrial exploitation of this thermophilic Gloeocapsa gelatinosa for the production of EPSs with several biotechnological applications in the food, medicine, pharmaceutical and related fields.