Optimization of culture medium for exopolysaccharide production by native strains of Lactobacillus fermentum, Lactobacillus plantarum, and commercial strain of Lactobacillus acidophilus

Exopolysaccharides, compounds derived from the metabolites of probiotic bacteria, play an important role in regulating the immune system. Considering the role of culture medium in the production efficiency of exopolysaccharides, the aim of this investigation was to optimize the culture medium for the production of exopolysaccharides by Lactobacillus fermentum, Lactobacillus plantarum, and Lactobacillus acidophilus. In addition, the effect of dextrose and sucrose on the production of exopolysaccharide was investigated using paper disks impregnated with probiotic culture medium. Then, the production efficiency and inhibitory power of exopolysaccharide free radicals were investigated in the culture medium after whey alone and with yeast extract and peptone. Sucrose as a carbon source of optimal culture medium for the production of exopolysaccharide is more suitable than dextrose. In addition, the production efficiency and inhibition of free radicals by exopolysaccharides of native probiotic strains in all culture media was significantly higher than commercial strains, which could be due to different enzyme mechanisms. In the cell wall of L. fermentum and L. plantarum is involved in the breakdown of sugars, which plays an important role in the formation of the final structure of the exopolysaccharide. Therefore, it is suggested that for L plantarum and L fermentum, YS culture medium with high production efficiency should be used and there is no significant difference for ATCC bacteria. For medicinal use, we recommend YD culture medium for NIMBB003 bacteria, SS culture medium for NIMBB014 bacteria, and SD culture medium for ATCC bacteria, which has better antioxidant properties and efficiency.