Influence of culture conditions on the production of extracellular polymeric substances (EPS) by Arthrospira platensis

Abstract Arthrospira platensis is a cyanobacterium that is of great biotechnological interest, particularly for the food industry, as it possesses a high content of proteins, pigments, lipids and carbohydrates. Cyanobacteria produce extracellular polymeric substances (EPS), which are co-products of secondary metabolism that present thickening or gelling properties. A 3-level factorial design was used to study the combined effect of different nitrate concentrations and photon flux density (PFD) values to evaluate the biomass and EPS production of A. platensis. The best result in terms of biomass production was obtained under condition 6 (2 g.L-1 NaNO3 and 600 μE.m-2.s-1) yielding a concentration of 1.292 g.L-1. However, condition 1 (0.25 g.L-1 NaNO3 and 200 μE.m-2.s-1) produced the greatest EPS yield (111 mg.g-1), followed by condition 9 (2 g.L-1 NaNO3 and 1000 μE.m-2.s-1). FTIR analyses of EPS samples indicated the presence of carboxylate and sulfate functional groups, and rheological studies of the EPS at 5 and 10 g.L-1 revealed a dilute solution behavior.