發(fā)布時(shí)間：2018-06-26 19:03

  本文選題：甲基營(yíng)養(yǎng)型芽孢桿菌 + 微生物絮凝劑��； 參考：《廣西大學(xué)》2015年碩士論文

【摘要】：采用常規(guī)的平板劃線分離方法從土壤樣品中分離得到130多種具有絮凝活性的菌株,通過(guò)菌株發(fā)酵液對(duì)高嶺土懸濁液的絮凝率考察產(chǎn)絮凝劑菌株的絮凝活性,得到了一株具有較高絮凝活性的菌株C412。通過(guò)平板菌落形態(tài),生理生化試驗(yàn)和16S rDNA及GyrB同源性序列分析結(jié)果,確定菌株C412為甲基營(yíng)養(yǎng)型芽孢桿菌。從絮凝活性分布發(fā)現(xiàn)菌株C412的胞外分泌物起到了主要的絮凝作用,然后將發(fā)酵液離心后,從上清液中提取到微生物絮凝劑。利用紫外和紅外等光譜分析,發(fā)現(xiàn)微生物絮凝劑MBF412的化學(xué)組分主要由多糖構(gòu)成。通過(guò)化學(xué)方法檢測(cè)菌株C412分泌的胞外微生物絮凝劑MBF412,其含有57.3%的總糖和1.7%的總蛋白質(zhì)含量。利用凝膠滲透色譜GPC發(fā)現(xiàn)微生物絮凝劑MBF412的分子量為3.47×105 g/mol,屬于天然高分子物質(zhì)。采用響應(yīng)面方法優(yōu)化了菌株生長(zhǎng)的培養(yǎng)基組分(g/L)：可溶性淀粉(19.73),牛肉膏(1.35),硫酸銨(3.05),氯化鈉(1),磷酸二氫鉀(2),磷酸氫二鉀(5)和硫酸鎂(0.05),pH為7.63。在此培養(yǎng)基中進(jìn)行驗(yàn)證實(shí)驗(yàn),產(chǎn)絮凝劑菌株C412對(duì)高嶺土懸濁液的最佳絮凝活性可達(dá)98.27%,微生物絮凝劑的產(chǎn)率約為4.25 g/L。并且,菌株C412在高濃度下的間歇式發(fā)酵表明：在搖瓶中的常規(guī)接種發(fā)酵時(shí),菌株出現(xiàn)最佳絮凝活性的時(shí)間為13～17小時(shí)；在1.5 L發(fā)酵罐中發(fā)酵時(shí),菌株出現(xiàn)最佳絮凝活性的時(shí)間縮短到2-6小時(shí),這為低成本規(guī)模化生產(chǎn)微生物絮凝劑提供了有效的思路。同時(shí)微生物絮凝劑的相關(guān)特性研究表明：該微生物絮凝劑具有較佳的耐熱性和耐酸堿性,從pH(4～13)和溫度(4～60℃)均具有較佳的絮凝率,具有較廣的應(yīng)用范圍,這歸功于微生物絮凝劑的主要組分多糖和極性官能團(tuán)。通過(guò)熒光定量PCR方法建立了甲基營(yíng)養(yǎng)型芽孢桿菌中的絮凝相關(guān)基因katE,pepT,sacA及scrR和菌株絮凝活性之間的關(guān)系。此外,利用Zeta電位,初步探索了微生物絮凝過(guò)程中涉及到的兩步沉淀機(jī)理(電中性機(jī)理和架橋機(jī)理)。本論文也證明了微生物絮凝劑MBF412的潛在工業(yè)應(yīng)用價(jià)值。
[Abstract]:More than 130 strains with flocculating activity were isolated from soil samples by conventional plate line separation method. The flocculating activity of flocculant producing strains was investigated by the flocculation rate of the fermentation broth on kaolin suspensions. A strain C412 with high flocculation activity was obtained. Based on the results of colony morphology, physiological and biochemical tests, 16s rDNA and GyrB homology analysis, the strain C412 was identified as methyl-nutritious Bacillus. The extracellular secretion of strain C412 was found to play a major role in flocculation from the distribution of flocculating activity. Then the fermentation broth was centrifuged and the microbial flocculant was extracted from the supernatant. The chemical composition of microbial flocculant MBF412 was mainly composed of polysaccharides by UV and IR spectra. The extracellular microbial flocculant MBF412 secreted by strain C412 contained 57.3% of total sugar and 1.7% of total protein. The molecular weight of microbial flocculant MBF412 was found to be 3.47 脳 10 ~ 5 g / mol by gel permeation chromatography (GPC). The medium components (g / L) of strain growth were optimized by response surface method: soluble starch (19.73), beef paste (1.35), ammonium sulfate (3.05), sodium chloride (1), potassium dihydrogen phosphate (2), potassium hydrogen phosphate (5) and magnesium sulfate (0.05) at pH 7.63. The optimum flocculation activity of flocculant producing strain C412 on kaolin suspension was 98.27 and the yield of microbial flocculant was about 4.25 g / L. In addition, the batch fermentation of strain C412 at high concentration showed that the optimum flocculation activity of the strain was 1317 hours when the strain was inoculated in shaking flask, and when fermented in 1.5 L fermentor. The optimum flocculation time of the strain was shortened to 2-6 hours, which provided an effective way for the production of microbial flocculant on a low cost scale. At the same time, the relative characteristics of the microbial flocculant showed that the microbial flocculant had better heat resistance and acid and alkali resistance, and had a better flocculation rate from pH (4 ~ 13) and temperature (40 ~ 60 鈩，

本文編號(hào)：2071088