星状双歧杆菌22-5产胞外多糖的研究

发布时间：2018-05-27 22:40

  本文选题：星状双歧杆菌 + 胞外多糖　； 参考：《中国农业大学》2005年硕士论文

【摘要】：双歧杆菌(Bifidobacterium)是人和动物肠道内重要的生理性细菌,它的存在直接影响消化道的健康状况。目前国外有关双歧杆菌胞外多糖(Exopolysaccharides,EPS)研究的报道寥寥无几,而国内则处于一片空白。基于此研究现状,立题于双歧杆菌EPS,旨于为进一步开发新型EPS提供方向,并为研究双歧杆菌生理功能的机理奠定基础。具体展开了下列研究工作: 1)从大量样品中分离筛选出一株具有较强产EPS能力的双歧杆菌菌株22-5,菌株经Biolog全自动微生物鉴定仪初步鉴定为星状双歧杆菌。经回收率试验确定苯酚-硫酸法为检测此EPS的方法。 2)对星状双歧杆菌22-5产EPS的培养条件和培养基组成进行了优化。结果表明,最佳培养条件为25℃恒温厌氧培养24h且培养基初始pH值为5.5;通过单因素确定最佳碳源、氮源、刺激因子后采用三元二次回归正交旋转设计进行优化。优化后EPS产量达到1.21g/L,是初始培养条件下产量的6倍多。 3)对星状双歧杆菌22-5所产的EPS进行提取及分离纯化条件的优化,确定了提取纯度高且EPS损失较小的方法路线,即:收集发酵上清液→浓缩→乙醇沉淀→脱蛋白→透析→Sepharose CL-6B凝胶层析。通过对Sepharose CL-6B琼脂糖凝胶纯化EPS条件的摸索,得到可洗脱下对称单一多糖峰的条件:0.05M NaCl作洗脱剂,30mL/h的洗脱速度。采用UV和HPLC分析鉴定,证明此EPS成分单一,具有较高的纯度。 4)经HPLC法检验,得知菌株22-5 EPS的分子量为3.92×10~5Da。菌株22-5所产的EPS具有较高的粘度,其随着温度的升高粘度不断降低,其粘度对酸和离子强度稳定,但对碱不稳定。此多糖对病原菌的抑制作用不明显,对乳酸菌的生长有一定的促进作用;通过DPPH自由基的验证说明其清除自由基的能力较强;可显著增强菌株22-5对肠上皮细胞Caco-2的粘附作用。
[Abstract]:Bifidobacterium (Bifidobacterium) is an important physiological bacteria in human and animal intestines. Its existence directly affects the health of digestive tract. At present, there are few reports about Exopolysaccharide of Bifidobacterium Exopolysaccharide EPSs in foreign countries, but there is a blank in our country. Based on the present situation of this research, the thesis is aimed at providing a direction for the further development of new EPS and laying a foundation for studying the mechanism of physiological function of Bifidobacterium. The following studies were carried out: 1) A Bifidobacterium strain 22-5 was isolated from a large number of samples and identified as Bifidobacterium stellate by Biolog automatic microbiological identification instrument. The phenol-sulfuric acid method was determined by the recovery test for the determination of this EPS. 2) the culture conditions and medium composition of EPS production by Bifidobacterium stellate 22-5 were optimized. The results showed that the optimum culture conditions were constant temperature anaerobic culture at 25 鈩，

本文编号：1944113