Comparisons of Functional Properties of Polysaccharides from Nostoc flagelliforme under Three Culture Conditions

Nostoc flagelliforme is an edible cyanobacterium with excellent food and herbal values. It has been used as food in China for more than 2000 years. Many studies have been focused on improving the yield and bioactivity of Nostoc flagelliforme polysaccharides although these have ignored the functional properties. In this study, we extracted and purified three polysaccharides (WL-CPS, NaCl-CPS and Glu-CPS) from Nostoc flagelliforme under normal, salt stress and mixotrophic culture conditions, respectively, in order to change the physicochemical properties of polysaccharides with the aim of obtaining better functional properties. Both salt stress and mixotrophic culture conditions increased the specific yield of polysaccharides. Their functional properties were comparatively investigated and the results showed that NaCl-CPS exhibited the highest emulsification activity and flocculation capability, which was also higher than that of some commercial products. In contrast, Glu-CPS exhibited the highest water and oil holding capacities, foaming property, intrinsic viscosity and bile acids binding capacity. Our results indicated that both NaCl-CPS and Glu-CPS could be considered to be functional polysaccharides according to their respective characteristics, which have great potential in numerous applications, such as food, pharmaceutical, cosmetic, chemical and mineral industries. These findings also demonstrated the potential application of the proper regulation of culture conditions in the development of polysaccharides with desired functional properties.