Isolation, Purification and Structural Properties Analysis of Exopolysaccharide from Leuconostoc pseudointestinalis HDL-3

A strain of lactic acid bacteria (LAB) with high production of exopolysaccharides (EPS) was isolated and screened from the fermentation broth of natural sauerkraut in Northeast China. The strain was identified as Leuconostoc pseudomesenteroides HDL-3 by 16S rDNA. This strain was used to produce EPS by fermentation. EPS was isolated and purified, and the structure and properties of EPS were analyzed. The results showed that the EPS was a linear glucan linked by α-(1, 6) glycosidic bonds. The molecular weight was 1.581×10⁶ Da. The EPS presents a smooth, shiny and compact sheet-like amorphous structure. The solubility, water-holding capacity were 98.63%±1.03% and 401.30%±4.92%, respectively. In addition, the EPS showed the shear dilution characteristics of non-Newtonian fluid. The viscosity was positively correlated with concentration and negatively correlated with temperature and pH. It not only had strong emulsifying ability for soybean oil, sunflower seed oil and benzene, but also had good scavenging ability for DPPH and ABTS.