Studies On The Phosphorylated Exopolysaccharide From Lactococcus Lactis Subsp.Lactis And Its Bioactivity

In this paper, Lactococcus Lactis subsp.Lactis was used as a raw material, we report here extraction parameters, optimization of phosphorylation, function characteristics, antioxidant activities of exopolysaccharide from Lactococcus Lactis subsp.Lactis(LAB EPS). Main results are lists as follows:1. Optimization for phosphorylation of EPSThe result shows that the maximum extraction yield of EPS was5.44g/L when the enrichment multiples was4. The protein was removed by trichloroacetic acid(TCA), the rate of protein removal could reach78.9%.The EPS was firstly separated through acolumn of DEAE-cellulose-52. As a result, three independent elution peaks were obtained. The first elution peak (between11-21tube) was the main research object which has the largest peak area and the highest content of polysaccharide.The first fraction was loaded onto a column of Sepharose4B. As a result, two independent elution peak were obtained. The first elution peak (between7-15tube) was the main research object which has the largest peak area and the highest content of polysaccharide.The phosphorylation conditions for exopolysaccharide from Lactococcus Lactis subsp.Lactis was studied. Several factors, such as the quantity of phosphorylate dreagents, temperature, time and pH were investigated and the quantity of phosphate were obtained from the orthogonal test. The optimum phosphorylation conditions for exopolysaccharide from Lactococcus Lactis subsp. Lactis were as follows:the ratio of exopolysaccharide to phosphorylated reagents is6, temperature90℃, time4h, pH6.0. Under these conditions, the quantity of phosphate was1.639mg/g.2. Chemical characterization of PEPSThe chemical characterization of EPS were investigated by various methods. As to CEPS, EPS-1, EPS-2and PEPS, polysaccharides content, measured by employing the method of sulfuric acid-phenol coloration, was32.08%,42.74%,88.93%and59.61%, respectively. Uronic acid content, determined by using the method of carbazole and sulphuric acid assay, was13.28%,13.14%,9.9%and7.93%, respectively. Protein content, measured by applying the method of coomassie brilliant blue coloration, was2.69%,0.57%, not detected and not detected, respectively. Antioxidant activities in vitro of EPS-2and PEPS were measured by using the chemical methods. Results show that:Hydroxyl radical scavenging activity increased in the order of EPS-2<PEPS<Vc. For superoxide radical, the scavenging activity increased in the order of EPS-2<PEPS. The reducing powers increased in the order of PEPS<EPS-2<Vc. The DPPH radical scavenging activity increased in the order of EPS-2<PEPS<Vc.3. The protection of D-Gal induced aging mice administers with PEPSIn antioxidant assays in vivo, mice were subcutaneously injected with D-galactose(D-Gal) for7weeks and administers PEPS via gavage simultaneously. As a result, PEPS administration significantly enhanced the activities of antioxidant enzymes and antioxidant capacity and decreased the levels of malondialdehyde in serums, hearts, livers, kidneys and spleens of aging mice. These results suggests that PEPS had potent antioxidant activities and could be explored as novel natural antioxidant.