Increased C-phycocyanin extract purity by flocculation of Arthrospira platensis with chitosan

Abstract

This paper demonstrates the possibility of harvesting cyanobacteria Arthrospira platensis at various growth phases followed by the extraction of purer C-phycocyanin from the flocculated biomass, by using chitosan as a flocculating agent. It was found that the flocculation efficiency was higher than 90% in 15 min for the chitosan concentrations of 50 and 100 mg/L, regardless of the growth phase. The C-phycocyanin purity (A620/A280) correlates with chitosan concentration and reaches the values of 1.6–1.9 for the chitosan concentrations of 50 and 100 mg/L with the growth phase dependence. C-phycocyanin extracted from the flocculated (by 50 and 100 mg/L of chitosan) biomass also had enhanced thermal stability as clearly demonstrated by an increase in a residual concentration from 55% to 85–91% when compared with the control after incubation at 60 °C for 150 min. Nevertheless, antioxidant activity of C-phycocyanin extracts obtained after flocculation processes was 28–37% less compared with the control samples. Thus, the use of chitosan as a flocculating agent for cyanobacteria A. platensis harvesting reduces the time of biomass collecting, increases extracted C-phycocyanin thermal stability and purity (on average, 1.5 times compared with the control), which makes it possible to use it in the food and cosmetic industries, bypassing a purification stage and stabilizing agents addition.