小分子右旋糖酐的体外益生效果评价

In Vitro Probiotic Effects of Dextran with a Small Molecular Weight

摘要:

目的 探究小分子右旋糖酐（SDex）对肠道微生物活性的影响。方法 选取自制的仅含α-1，6-糖苷键的SDex为研究对象，采用双歧杆菌属、乳杆菌属、大肠杆菌、肠粪肠球菌等9种典型肠道微生物进行体外发酵，并对SDex的益生效果进行评价。考察其发酵过程中微生物增殖及产酸情况，并与商品化右旋糖酐20（Dex 20）、低聚异麦芽糖（IMOs）进行对比。结果 Dex 20对微生物生长没有促进效果，而SDex和IMOs均能显著促进双歧杆菌、乳杆菌等益生菌的增殖，并使其代谢产生有机酸。与IMOs相比，SDex不能促进条件致病菌大肠杆菌的生长，对中性菌粪肠球菌的促进作用也较弱。SDex和IMOs对益生菌产乳酸的影响无显著差异，但SDex可促进益生菌产生更多乙酸，而IMOs可使益生菌产生更多甲酸。结论 SDex具有促进双歧杆菌、乳杆菌增殖而不促进大肠杆菌增殖的选择性益生功能，这对补充现有的益生元具有重要意义。

Abstract:

Objective The aim of this study is to explore the effects of dextran with a small molecular weight (SDex) on the viability of intestinal microorganisms.Method The probiotic effects of laboratory-designed SDex containing only α-1,6 glycosidic bonds was evaluated by in vitro fermentation with nine typical intestinal strains, including strains from the genera Bifidobacterium and Lactobacillus, as well as species such as Escherichia coli and Enterococcus faecalis. The microbial proliferation and organic acid production during fermentation were compared among SDex, commercial dextran 20 (Dex 20), and isomalto-oligosaccharides (IMOs).Result SDex and IMOs significantly promoted the proliferation of probiotics such as Bifidobacterium and Lactobacillus as well as the production of organic acids, while Dex 20 showed little effects. SDex did not promote the growth of the conditionally pathogenic bacterium Escherichia coli but showed a less positive effect on the neutral bacterium Enterococcus faecalis than IMOs. Neither SDex nor IMOs significantly affected the lactic acid production. However, SDex promoted acetic acid production while SDex enhanced formic acid production by probiotics.Conclusion SDex demonstrates selective probiotic effects of promoting the proliferation of Bifidobacterium and Lactobacillus while exerting little effect on Escherichia coli, which indicates SDex is essential for replenishing existing prebiotics.