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

Abstract

Arthrospira platensis is a cyanobacterium that exhibits a large biotechnological interest for the food industry because of its high protein content, pigments, lipids and carbohydrates. The extracellular polymeric substances (EPS) are co-products of secondary metabolism that may present thickening or gelling property. A 3-level factorial design was used to study the combined effect of different nitrate concentrations and photon flux density (PFD) to evaluate the biomass and EPS production by Arthrospira platensis. The best result for biomass production was obtained under condition 6 (2 g.L-1 NaNO3 and 600 µE.m-2s-1) leading a biomass concentration of 1.292 mg.L-1. Condition 1 (0.25 g.L-1NaNO3 and 200 µE.m-2s-1) produced the major EPS yield (111 mg.g-1) followed by condition 9 (2 g.L-1NaNO3 and 1000 µE.m-2s-1). The present of carboxylate and sulfate functional groups was identified in EPS samples. Rheological studies performed for some EPS products at 5 and 10 g.L-1 concentrations revealed a dilute solution behavior.