香菇菌糠寡糖提取的研究

发布时间：2018-01-19 01:29

  本文关键词： 香菇菌糠 寡糖 膜分离 枯草芽孢秆菌 发酵　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：菌糠是子实体采收后产生的废弃培养基,一般包括麦麸、木屑和剩余菌丝体,不加处理随意弃置或简单进行焚烧处理,不仅会增加环境中蚊蝇和病原微生物的数量,还会释放糖类、蛋白质等污染水质,造成环境污染。糖类等胶体物质、混凝剂絮体等颗粒物质及富里酸等溶解性有机物在饮用水处理过程中会造成膜污染。超滤膜过滤过程中,截留的胶体层主要是水中普遍存在的多糖,而水中的金属离子如钙离子和铁离子会连接不同的多糖分子,使其在膜表面形成比滤饼层结构更加紧密的凝胶层。本研究以综合利用的思路,利用膜分离技术,从废弃物香菇菌糠中最大限度提取香菇寡糖,降低环境污染,实现对菌糠的高附加值利用。膜分离技术在水处理领域有广泛应用,具有高效、节能等特点,非常适合从菌糠中提取寡糖。寡糖分子量介于单糖和多糖之间,即200KD～3000 KD。首先利用超滤可去除溶液中相对分子量大于3000 KD的多糖,再利用纳滤膜,除去溶液中相对分子量小于200 KD的单糖。为了提高寡糖得率,从香菇菌糠中筛选出可以降解多糖为寡糖的菌种,采用微生物发酵香菇菌糠的方法,将香菇多糖降解为寡糖,提高寡糖产量。经发酵后,寡糖产率从原来的0.29%提高到0.71%。本研究涉及香菇子实体糖类提取工艺、卷式膜分离寡糖工艺的优化、活性炭脱色、微生物发酵香菇菌糠四个方面。香菇子实体中寡糖含量较香菇菌糠中含量要高,且试验干扰因素少,拟以香菇子实体为试材,选择料液比、浸提温度、浸提时间进行正交试验,优化寡糖的生产工艺;改变过滤操作压力和料液pH,优化出最佳膜工艺;改变活性炭脱色条件(活性炭添加量、时间、温度),分离纯化寡糖;最后利用微生物的发酵作用,从菌糠里筛选出可以提高寡糖产量的微生物菌种,经过发酵最大限度提高寡糖提取率。取得的主要研究成果:(1)料液比1:16,提取温度60℃,提取时间1Omin,在此工艺下从香菇子实体中提取寡糖的产率为1.07%;(2)超滤膜操作压力0.75MPa,纳滤膜1.95MPa,pH为7时为膜处理最佳工艺;(3)活性炭用量0.3g/100mL、脱色时间1Omin、脱色温度60°C时,脱色效果最好,脱色率为74.1%;(4)从食用菌菌糠中筛选出能够降解香菇多糖的菌株,经16SrDNA序列检测和比对后,鉴定为为枯草芽孢秆菌,利用该菌株可以大幅增加菌糠提取寡糖的效率,在接种量7.5%,40℃、发酵48h后,以1:24料液比,50℃浴加热1Omin时,香菇菌糠中寡糖产率为0.71%,与没有进行枯草芽孢秆菌发酵的对照相比,提取率提高2.5倍。
[Abstract]:Bacterial bran is a waste medium produced after harvest of fruiting body. It usually includes wheat bran, sawdust and residual mycelium, and is disposed of at will or simply incinerated without treatment. Not only will increase the number of mosquitoes and pathogenic microorganisms in the environment, but also will release sugar, protein and other pollution of water quality, resulting in environmental pollution, sugar and other colloidal substances. Flocculant flocs and dissolved organic compounds such as fulvic acid can cause membrane fouling in the process of drinking water treatment. The metal ions in water such as calcium ion and iron ion will connect different polysaccharide molecules to form a gel layer which is more compact than the filter cake layer structure on the membrane surface. Lentinus edodes oligosaccharides were extracted from the waste of Lentinus edodes to reduce environmental pollution and achieve high value-added utilization. Membrane separation technology has been widely used in the field of water treatment with the characteristics of high efficiency and energy saving. It is very suitable for extracting oligosaccharides from bacterial bran. The molecular weight of oligosaccharides is between monosaccharides and polysaccharides. That is 200kD ~ 3000KD. Firstly, the polysaccharides with relative molecular weight larger than 3000KD can be removed by ultrafiltration, and then nanofiltration membrane is used. In order to increase the yield of oligosaccharides, the strains which can degrade polysaccharides into oligosaccharides were screened out from the mushroom bran, and the method of microbial fermentation was used to ferment the mushroom chaff of Lentinus edodes. Lentinus edodes polysaccharides were degraded into oligosaccharides and the yield of oligosaccharides was increased from 0.29% to 0.71 after fermentation. Optimization of the separation process of oligosaccharides by coil membrane, decolorization of activated carbon and microbial fermentation of mushroom bran. The content of oligosaccharide in the fruiting body of Lentinus edodes is higher than that in shiitake mushroom bran, and the interference factors are less. In order to optimize the production process of oligosaccharides, orthogonal experiments were carried out with lentinus edodes fruiting body as the material, the ratio of material to liquid, the extraction temperature and the extraction time. The optimum membrane process was optimized by changing the filtration pressure and the pH of the liquid. Changing the decolorization conditions of activated carbon (amount of activated carbon, time, temperature), separation and purification of oligosaccharides; Finally, by using the fermentation effect of microorganism, the microbial strains which can increase the yield of oligosaccharide were selected from the microbial chaff. After fermentation, the extraction rate of oligosaccharides was maximized. The main research result was: 1: 16 ratio of material to liquid, extraction temperature 60 鈩，

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