论文总字数：21117字

摘 要

铁皮石斛具有较高的药用价值，它的主要功能成分为石斛多糖。本文对1种水提石斛多糖和3种碱提石斛多糖进行分子量分布测定、单糖组成分析、紫外色谱分析、红外色谱分析，并以石斛多糖为碳源进行保加利亚乳杆菌的培养。实验结果表明，水提石斛多糖（WEDP-1）的平均分子量为6.71×10⁵ u，3种碱提石斛多糖（AEDP-1、AEDP-2、 AEDP-3）的平均分子量分别约为1.78×10⁶、2.03×10⁶和1.88×10⁵ u。甘露糖和葡萄糖是WEDP-1的主要组成成分，葡萄糖、半乳糖、木糖和阿拉伯糖是AEDP-1、AEDP-2、AEDP-3的主要组成成分。4种石斛多糖都存在β-构型的糖苷键和吡喃环结构。石斛多糖对保加利亚乳杆菌促生长作用最适浓度为2%。AEDP-2促进保加利亚乳杆菌生长效果最好。石斛多糖发酵时主要产生乙酸、丙酸和乳酸。4种石斛多糖的丙酸产量明显高于阳性对照，AEDP-2在2%浓度下，产丙酸浓度最高达到5.44g/L。本研究将为分析石斛多糖促进保加利亚乳杆菌生长的构效关系提供有用信息。

关键词: 铁皮石斛 多糖 保加利亚乳杆菌 发酵 短链脂肪酸

Promoting Effect of Polysaccharides from Dendrobium offcinale on the Growth of Lactobacillus bulgaricus

Abstract

Dendrobium officinale has high medicinal value, and it contains several kinds of polysaccharides with different molecular weights as functional components. In this paper, the molecular weight distribution analysis, monosaccharide composition analysis, UV chromatography and infrared chromatographic analysis of polysaccharides from D. officinale, and the culture of Lactobacillus bulgaricus were carried out. Four Dendrobium polysaccharides were used as carbon source. The experimental results showed that the average molecular weight of the water-extracted polysaccharide (WEDP-1) was 6.71×10⁵ u, and the average molecular weight of the three kinds of alkali-extracted polysaccharides (AEDP-1, AEDP-2, AEDP-3) was 1.78×10⁶, 2.03×10⁶ and 1.88×10⁵ u, respectively. WEDP-1 was mainly composed of mannose and glucose, while AEDP-1, AEDP-2 and AEDP-3 were mainly composed of glucose, galactose, xylose and arabinose. All the four kinds of polysaccharides had β-configuration glycoside bond and pyran ring structure. The optimal concentration of Dendrobium polysaccharide on the growth of Lactobacillus bulgaricus is 2%. Among the four polysaccharides, the most promoting polysaccharide was AEDP-2. The fermentation of polysaccharides mainly produced acetic acid, propionic acid and lactic acid. The propionic acid production with four polysaccharides was significantly higher than that of the positive control. The concentration of propionic acid produced by AEDP-2 at the concentration of 2 % reached 5.44 g/L. This study provided useful information for analyzing the structure-activity relationship of polysaccharides from D. officinale to promote the growth of L. bulgaricus.

Key Words: Dendrobium officinale; Polysaccharides; Lactobacillus bulgaricus; Fermentation; Short-chain fatty acid

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1 石斛多糖 1

1.1.1 石斛的化学成分 1

1.1.2 石斛多糖的单糖组成 1

1.1.3 石斛多糖的分子量分布 1

1.1.4 石斛多糖的生物活性 2

1.2 益生菌 2

1.2.1 益生菌定义与分类 2

1.2.2 益生菌的益生作用 3

1.2.3 保加利亚乳杆菌的生理特性 3

1.3 多糖的益生元作用 4

1.3.1 益生元定义与分类 4

1.3.2 乳酸菌生长促进作用 4

1.3.3 乳酸菌产酸促进作用 4

1.4 现有研究中存在的问题 5

1.5 本研究的目的及意义 5

1.5.1 研究目的 5

1.5.2 研究意义 5

1.6 研究内容 5

第二章 实验材料与方法 6

2.1 实验材料 6

2.1.1 铁皮石斛多糖 6

2.1.2 试剂与仪器 6

2.2 实验方法 7

2.2.1 石斛多糖的分子量分布测定 7

2.2.2 石斛多糖的单糖组分分析 8

2.2.3 石斛多糖的UV光谱分析 10

2.2.4 石斛多糖的IR光谱分析 10

2.2.5 保加利亚乳杆菌培养 10

2.2.6 保加利亚乳杆菌生长和产酸能力测定 12

第三章 结果与讨论 14

3.1 石斛多糖的分子量分布 14

3.2 石斛多糖的单糖组成 14

3.3 石斛多糖的UV光谱 15

3.4 石斛多糖的IR光谱 15

3.5 石斛多糖对保加利亚乳杆菌生长的影响 16

3.6 石斛多糖对保加利亚乳杆菌产酸的影响 19

第四章 结论与展望 22

4.1 结论 22

4.2 展望 22

参考文献 23

致 谢 27

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