Production and characterization of extracellular carbohydrate polymer from Cyanothece sp. CCY 0110

► The marine cyanobacterium Cyanothece sp. CCY 0110 is an efficient RPS producer. ► Amount of carbohydrates released is mainly related to the number of cells (growth). ► Light is a key factor with high light intensities enhancing RPS production. ► RPS: Nine residues (two uronic acids), sulfate groups, peptides, thermostable, amorphous. ► Potential for biotechnological applications. Cyanobacterial extracellular polymeric substances (EPS) are heteropolysaccharides that possess characteristics suitable for industrial applications, notably a high number of different monomers, strong anionic nature and high hydrophobicity. However, systematic studies that unveil the conditions influencing EPS synthesis and/or its characteristics are mandatory. In this work, Cyanothece sp. CCY 0110 was used as model organism. Our results revealed that this strain is among the most efficient EPS producers, and that the amount of RPS (released polysaccharides) is mainly related to the number of cells, rather than to the amount produced by each cell. Light was the key parameter, with high light intensity enhancing significantly RPS production (reaching 1.8gL−1), especially in the presence of combined nitrogen. The data showed that RPS are composed by nine different monosaccharides (including two uronic acids), the presence of sulfate groups and peptides, and that the polymer is remarkably thermostable and amorphous in nature.