本文選題：乳清粉　切入點：生物轉化　出處：《天津科技大學》2017年碩士論文　論文類型：學位論文

【摘要】：醛糖酸作為糖的衍生物是糖經氧化生成的羧酸,其中麥芽糖酸、乳糖酸、半乳糖酸、纖維二糖酸、鼠李糖酸及其鹽類在食品和醫(yī)藥等行業(yè)有著廣泛的用途,越來越受到關注。其制備方法大致分為化學法和發(fā)酵法,化學催化合成法產生多種副產物導致分離、純化困難。而微生物轉化法來制備糖酸具有轉化率高,副產物少等優(yōu)點。但篩選獲得具有高的或新的催化活性的菌株用于糖酸的生產仍然非常重要。本文對具有糖酸轉化能力的假單胞菌進行篩選,獲得高效轉化菌株并對其全細胞轉化條件進行優(yōu)化,進一步研究利用乳清作為培養(yǎng)基生產乳糖酸的轉化工藝。通過高效液相色譜、質譜和核磁分析法對轉化產物進行確定,發(fā)現(xiàn)天仙果假單胞菌TCCC11959僅能轉化生成麥芽糖酸,甜菜假單胞菌TCCC11961轉化生成麥芽糖酸和乳糖酸,而莓實假單胞菌TCCC11892轉化生成麥芽糖酸、乳糖酸、半乳糖酸、纖維二糖酸、鼠李糖酸。其中,利用莓實假單胞菌轉化生成半乳糖酸、纖維二糖酸以及鼠李糖酸為首次報道。采用單因素法對莓實假單胞菌TCCC11892的轉化條件進行優(yōu)化,假單胞菌靜息細胞轉化乳糖、半乳糖、纖維二糖、鼠李糖的最優(yōu)條件均為:溫度37℃, OD600=40,轉速180 rpm;轉化效率由大到小依次為麥芽糖、乳糖、半乳糖、纖維二糖、鼠李糖。利用莓實假單胞菌TCCC11892批次轉化麥芽糖和乳糖生成麥芽糖酸和乳糖酸,當麥芽糖濃度為100 g/L時,轉化進行7批次,轉化率分別保持90%以上,當批次轉化實驗進行到第8次時,產率明顯下降。當乳糖濃度為100 g/L時,當批次轉化實驗進行到第11次時,產率明顯下降。利用乳清培養(yǎng)莓實假單胞菌TCCC11892同時轉化乳糖生成乳糖酸,當乳清粉濃度為20%時轉化率最高。在搖瓶實驗的基礎上,在1L發(fā)酵罐中進行乳糖酸生產,并研究溶氧對生產的影響,當發(fā)酵罐中溶氧為40%時,發(fā)酵27 h后,活菌數(shù)為2.37×1010CFU/mL,乳糖酸的產率達到86%。轉化結束后,離心收集上清,經乙醇沉淀、烘干等步驟得到乳糖酸產品。
[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，

本文編號：1618636