本文關(guān)鍵詞：重組大腸桿菌D303利用粗甘油產(chǎn)D-乳酸的研究　出處：《湖北工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： D-乳酸 大腸桿菌 粗甘油 混合碳源 離子交換

【摘要】：D-乳酸作為一種重要的有光學(xué)活性的手性中間體和聚合物單體,廣泛應(yīng)用于農(nóng)業(yè)、化工和醫(yī)藥等領(lǐng)域。D-乳酸工業(yè)生產(chǎn)的主要方法是發(fā)酵法,而利用甘油生產(chǎn)D-乳酸是一個(gè)熱點(diǎn)。但是存在的問題是菌體生長(zhǎng)緩慢、菌濃較低、產(chǎn)酸速率、底物阻遏等問題。為了解決這些問題,本文擬通過對(duì)粗甘油進(jìn)行脫色處理,并以葡萄糖和甘油作為混合碳源進(jìn)行發(fā)酵,用離子交換法結(jié)合減壓蒸餾對(duì)產(chǎn)物D-乳酸進(jìn)行分離純化。主要研究?jī)?nèi)容及結(jié)果如下:(1)通過對(duì)粗甘油用活性炭進(jìn)行不同條件下的脫色處理,并以脫色后的甘油進(jìn)行發(fā)酵評(píng)估其脫色效果,確定粗甘油脫色的最佳條件為:活性炭用量為3.5%,脫色時(shí)間為2 h,在此條件下甘油的脫色率和甘油得率分別為94.35%,93.8%。以4%、6%、8%、10%的脫色甘油為碳源,在發(fā)酵溫度為37℃,轉(zhuǎn)速為150 r/min的條件下,以5%的碳酸鈣為中和劑發(fā)酵72 h,D-乳酸產(chǎn)量分別為21.4 g/L、26.1 g/L、24.6 g/L、23.8 g/L。(2)通過初始甘油濃度對(duì)D-乳酸產(chǎn)量的影響,確定了最適碳源含量為5%;在5%總碳源下,研究了甘油與葡萄糖不同比例組成的混合碳源對(duì)發(fā)酵的影響。當(dāng)混合碳源中葡萄糖含量為10 g/L,甘油含量為40 g/L時(shí),產(chǎn)D-乳酸較快,產(chǎn)量較高為25.9 g/L。在7 L發(fā)酵罐中發(fā)酵,通過流加3 mo/L氫氧化鈣作為中和劑,E.coli D303以10 g/L葡萄糖和40 g/L甘油為底物,在pH為5.86,轉(zhuǎn)速為150 r/min,溫度為37℃條件下,發(fā)酵至23 h左右葡萄糖消耗完全,發(fā)酵至60 h,D-乳酸產(chǎn)量達(dá)到最大為40.8 g/L,剩余甘油濃度為4 g/L,糖酸轉(zhuǎn)化率為81.6%,其發(fā)酵至最大產(chǎn)量所用時(shí)間減少了8 h,產(chǎn)量提高了10.4 g/L。(3)通過離子交換樹脂對(duì)產(chǎn)物D-乳酸進(jìn)行分離,再通過減壓蒸餾對(duì)洗脫液進(jìn)行純化,其中對(duì)陰離子交換樹脂的吸附條件和洗脫條件做了研究。主要結(jié)果為:采用001×8強(qiáng)酸性苯乙烯陽離子交換樹脂去除陽離子;D371苯乙烯陰離子交換樹脂對(duì)發(fā)酵液中乳酸進(jìn)行分離時(shí),吸附流速為1.0 mL/min,吸附溫度為為25℃時(shí),對(duì)D-乳酸可以獲得較好的吸附效果;以水為洗脫劑,在洗脫溫度為90℃,洗脫流速為1.0 mL/min時(shí),洗脫效果最好;采用兩次減壓蒸餾,可得化學(xué)純度99%以上的乳酸。
[Abstract]:D- lactic acid as an important optically active chiral intermediates and polymer monomer, widely used in agriculture, the main methods of chemical and pharmaceutical fields of industrial production is.D- lactic acid fermentation, and the use of D- lactic acid production of glycerol is a hot topic. But the problem is the germ of slow growth, low concentration the acid production rate, substrate, repression and other issues. In order to solve these problems, this paper on the crude glycerin bleaching treatment, and with glucose and glycerol as mixed carbon source for fermentation, combined with vacuum distillation of D- lactic acid was purified by ion exchange method. The main research contents and results are as follows: (1) based on the crude glycerol with activated carbon decolorization treatment under different conditions, and after bleaching glycerol fermentation to evaluate the decolorization effect, determine the optimum conditions for decolorization of crude glycerol: activated carbon dosage is 3.5%, bleaching time 涓，

本文編號(hào)：1387144