【作者】 韦云路； 李全宏；

【Author】 Wei Yunlu;Li Quanhong;College of Food Science and Nutritional Engineering,China Agricultural University;

【机构】 中国农业大学食品科学与营养工程学院；

【摘要】 乳酸菌是一类公认的食用安全益生菌,乳酸菌胞外多糖是乳酸菌产生的活性代谢产物之一,具有抗氧化、抗菌、降低胆固醇、抗肿瘤等作用。前期研究通过发酵乳杆菌YL-11的基因组信息分析了该菌株胞外多糖的合成途径,测定了其抑癌活性。为进一步对发酵乳杆菌YL-11产生的胞外多糖的结构及生物活性进行研究,采用高效液相色谱、近红外光谱、甲基化等对多糖的组成和结构进行解析,并探究其体外抗氧化活性。结果表明,发酵乳杆菌YL-11的胞外多糖主要由葡萄糖和半乳糖组成,同时含有少量甘露糖和阿拉伯糖;该多糖的红外谱图存在3600～3200 cm^-1的吸收带,为-OH的伸缩振动吸收峰,此区域吸收峰是糖类的特征峰,同时存在归属于吡喃糖环的C-H变角振动吸收峰;甲基化分析得出该多糖中主要有9种糖苷键类型,分别为t-Araf,t-Glcp,t-Galp,→3)-Galp-（1→,→2）-Galp-（1→,→6）-Manp-（1→,→2,6）-Manp-（1→,→3,6）-Glcp-（1→和→3,6）-Galp-(1→;此外,该胞外多糖能够清除DPPH等自由基,具有抗氧化活性。本研究结果能够为乳酸菌胞外多糖作为功能性调节剂的应用提供更多理论支持。更多还原

【Abstract】 Lactic acid bacteria（LAB） are known as probiotics and generally recognized as safe（GRAS）.Exopolysaccharide is an active metabolite produced by LAB,which has been reported to exhibit antioxidant,antibacterial,cholesterol-lowering and anti-tumor activities.The synthesis pathway of an exopolysaccharide produced by a strain of Lactobacillus fermentum YL-11 has been determined based on the genome information,and its antitumor activity was measured.The structure and biological activity of this exopolysaccharide were further analyzed.The composition and structure of this exopolysaccharide from strain YL-11 were analyzed by high performance liquid chromatography,fourier-transformed infrared（FTIR） spectroscopy and methylation,and its antioxidant activity in vitro was further determined.The results showed that exopolysaccharide from strain YL-11 was mainly composed of glucose and galactose,with a small amount of mannose and arabinose.An absorption band of 3600-3200 cm^-1 was due to the stretching vibration absorption peak of-OH.The absorption peak in this region was a characteristic peak of sugars.There was also a C-H variable angle vibration absorption peak attributable to the pyranose ring in the FTIR spectrum.Methylation analysis shows that there were nine types of glycosidic bonds,including t-Araf,tGlcp,t-Galp,→3)-Galp-（1→,→2）-Galp-（1→,→6）-Manp-（1→,→2,6）-Manp-（1→,→3,6）-Glcp-（1→ and→3,6）-Galp-(1→.In addition,the exopolysaccharide has antioxidant activity,which can scavenge DPPH free radicals.The present findings provide more theoretical support for the application of lactic acid bacteria exopolysaccharides as functional regulators.更多还原