假单胞菌对醛糖酸的转化生产研究

发布时间：2018-03-16 06:07

  本文选题：乳清粉　切入点：生物转化　出处：《天津科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：醛糖酸作为糖的衍生物是糖经氧化生成的羧酸,其中麦芽糖酸、乳糖酸、半乳糖酸、纤维二糖酸、鼠李糖酸及其盐类在食品和医药等行业有着广泛的用途,越来越受到关注。其制备方法大致分为化学法和发酵法,化学催化合成法产生多种副产物导致分离、纯化困难。而微生物转化法来制备糖酸具有转化率高,副产物少等优点。但筛选获得具有高的或新的催化活性的菌株用于糖酸的生产仍然非常重要。本文对具有糖酸转化能力的假单胞菌进行筛选,获得高效转化菌株并对其全细胞转化条件进行优化,进一步研究利用乳清作为培养基生产乳糖酸的转化工艺。通过高效液相色谱、质谱和核磁分析法对转化产物进行确定,发现天仙果假单胞菌TCCC11959仅能转化生成麦芽糖酸,甜菜假单胞菌TCCC11961转化生成麦芽糖酸和乳糖酸,而莓实假单胞菌TCCC11892转化生成麦芽糖酸、乳糖酸、半乳糖酸、纤维二糖酸、鼠李糖酸。其中,利用莓实假单胞菌转化生成半乳糖酸、纤维二糖酸以及鼠李糖酸为首次报道。采用单因素法对莓实假单胞菌TCCC11892的转化条件进行优化,假单胞菌静息细胞转化乳糖、半乳糖、纤维二糖、鼠李糖的最优条件均为:温度37℃, OD600=40,转速180 rpm;转化效率由大到小依次为麦芽糖、乳糖、半乳糖、纤维二糖、鼠李糖。利用莓实假单胞菌TCCC11892批次转化麦芽糖和乳糖生成麦芽糖酸和乳糖酸,当麦芽糖浓度为100 g/L时,转化进行7批次,转化率分别保持90%以上,当批次转化实验进行到第8次时,产率明显下降。当乳糖浓度为100 g/L时,当批次转化实验进行到第11次时,产率明显下降。利用乳清培养莓实假单胞菌TCCC11892同时转化乳糖生成乳糖酸,当乳清粉浓度为20%时转化率最高。在摇瓶实验的基础上,在1L发酵罐中进行乳糖酸生产,并研究溶氧对生产的影响,当发酵罐中溶氧为40%时,发酵27 h后,活菌数为2.37×1010CFU/mL,乳糖酸的产率达到86%。转化结束后,离心收集上清,经乙醇沉淀、烘干等步骤得到乳糖酸产品。
[Abstract]:As a derivative of sugar, uronic acid is carboxylic acid formed by oxidation of sugar. Maltose acid, lactate acid, galactose acid, fibronecarboxylic acid, rhamnoxylic acid and its salts are widely used in food and medicine industries. More and more attention has been paid to it. Its preparation methods are generally divided into chemical method and fermentation method. Many by-products produced by chemical catalytic synthesis method lead to separation and purification, while microbial transformation method to prepare sugar and acid has high conversion rate. However, it is still very important to screen strains with high or new catalytic activity for the production of saccharic acid. High efficiency transformation strain was obtained and its whole cell transformation conditions were optimized. The conversion process of lactate production using whey as culture medium was further studied. The transformation product was determined by HPLC, MS and NMR. It was found that TCCC11959 could only convert to maltose acid, TCCC11961 to maltose acid and lactate acid, while TCCC11892 to maltose acid, lactate acid, galactose acid and fibronectic acid. Rhamnoxylic acid. Among them, galactosolic acid, fibronecanoic acid and rhamnoxylic acid were first reported by transformation of Pseudomonas raspberry. The transformation conditions of TCCC11892 were optimized by single factor method. The optimal conditions for the transformation of resting cells from Pseudomonas to lactose, galactose, cellobiose and rhamnose were as follows: temperature 37 鈩，

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