重组果聚糖蔗糖酶的发酵优化及应用

Study on Fermentation Optimization and Application of Recombinant Levansucrase

DOI：10.3969/j.issn.1673-1689.2019.04.015

中文关键词: 果聚糖蔗糖酶 发酵优化 低聚乳果糖

英文关键词: levansucrases,fermentation optimization,lactosucrose

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中文摘要:

为了研究不同条件下重组短小芽孢杆菌产果聚糖蔗糖酶的最适条件以及利用重组酶转化蔗糖-乳糖制备低聚乳果糖的最适转化条件。以前期构建的产果聚糖蔗糖酶重组短小芽孢杆菌Brevibacillus brevis/pNCMO2-lsc作为菌种，通过单因素试验以及正交试验确定其最适产酶的发酵培养基为：葡萄糖 20 g/L、氮源（工业酵母粉∶棉籽粉=2∶1，质量比）为40 g/L、CaCl2 0.5 mmol/L，最适产酶温度30 ℃。在最优条件下发酵培养，果聚糖蔗糖酶的酶活可达62.1 U/mL，是优化前的3.69倍。利用该重组果聚糖蔗糖酶转化蔗糖-乳糖制备低聚乳果糖，在蔗糖和乳糖质量浓度均为200 g/L情况下，确定其最适转化条件：反应温度35 ℃，pH 6.0，加酶量为2 U/g底物，反应8 h后低聚乳果糖转化率可达39.1%。

英文摘要:

In order to study the optimum conditions ofB. brevisproducing levansucrase and the optimum transformation conditions for the conversion of sucrose-lactose to lactosucrose by recombinant enzyme. A recombinant strain containing the encoding gene ofBacillus flexuslevansucrase，B. brevis/pNCMO2-Lsc had been constructed in our laboratory previously. The optimum fermentation medium was determined by single factor test and orthogonal test：20 g/L of glucose，40 g/L of nitrogen source（industrial yeast powder：cottonseed powder=2∶1），0.5 mmol/L of CaCl2，The optimal temperature for the enzyme production was 30 ℃. Under these conditions，the production of levansucrases reached 62.1 U/mL，which was 3.69 times higher than the original enzyme activity. The crude enzyme was used for the preparation of lactosucrose. Under the condition of sucrose and lactose concentration of 200 g/L，the optimum conditions were as follows：reaction temperature 35 ℃，pH 6.0，enzyme loading 2 U/g substrate，reaction time 8 h. Reaching 39.1%.

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