Junko Nishimura
Hachinohe Institute of Technology, Japan
Title: Polysaccharide of lactic acid bacteria using as yogurt starter
Biography
Biography: Junko Nishimura
Abstract
Strains producing exocellular polysaccharide (EPS) exist in daily lactic acid bacteria. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, both of which contain EPS producing strains, are generally used for fermented milk manufacture. They are widely used to improve texture and prevent syneresis in fermented dairy products. The physiological functions of EPS, such as reducing the cholesterol concentration in the blood as well as decreasing infectivity against influenza, have also been demonstrated. We investigated the relationship between the chemical structure and physiological functions of EPS on L. bulgaricus OLL 1073R-1. In our previous studies, it was found that this EPS constituted two kinds of polysaccharides, i.e., neutral polysaccharide (NPS) and acidic polysaccharide (APS), both of which had the same carbohydrate structure, but different phosphorus contents. APS induced B-cell mitogenic activity on murine lymphocytes, though NPS did not show it. In addition, APS was able to augment the cytotoxicity and the gene expression of several cytokines in macrophages. Based on these results, it is believed that the phosphorus group in EPS is important for modulating the immune response. Biosynthesis, phosphorylation, and the linkage of the phosphate group of NPS and APS from L. bulgaricus OLL1073R-1 are still unknown. Especially, the phosphorylation of bacterial EPS is rare. EPS production of L. bulgaricus had been obtained by the horizontal transmission of EPS gene in S. thermophilus, however, there is no report of EPS containing phosphorus in S. thermophilus. We are planning to further examine these details in the future