Bacillus subtilis levan sucrase mutant T305A and application thereof

Abstract

The invention relates to bacillus subtilis levan sucrase mutant T305A and an application thereof. The bacillus subtilis levan sucrase mutant T305A is obtained by using a modern molecular enzyme engineering technology for carrying out molecular modification on levan sucrase amino acid sequences derived from bacillus subtilis through error-prone PCR (Polymerase Chain Reaction) and active screening. The gene of the mutant T305A is inserted into pSE380 so as to construct a recombination vector which is guided into escherichia coli for host expression. Compared with a wild-type enzyme, the mutant enzyme has the advantages that the concentration and the tolerance of a substrate are obviously increased in a reaction process of forming levan by using cane sugar as the substrate for converting glucoside, when the highest conversion rate is reached, the concentration of the substrate is increased to 25% of the mutant enzyme from 10% of the wild-type enzyme, the batch yield and the utilization ratio of equipment are facilitated to be increased, and the production cost is reduced.

Description

technical field [0001] The invention relates to the field of biotechnology, in particular to a Bacillus subtilis levansucrase mutant T305A and an application thereof. Background technique [0002] Levan is a kind of high molecular weight fructan mainly derived from microorganisms, usually linked by β-(2,6) glycosidic bonds. Levan has been proven to have a variety of biological activities, and has certain effects in anti-tumor, anti-virus, and enhancing body immunity. Levan also has the function of enhancing immune stress and improving intestinal imbalance. It is an important food additive and can be used in the production of prebiotics, dietary fiber, low-calorie foods, weight loss products, and lipid-lowering products. It can also be used as an emulsifier , moisturizers, gels and more. In terms of moisturizing performance, levan has the same effect as hyaluronic acid, which is currently in high demand and expensive in the cosmetics industry, and has great potential for ap...

AI Technical Summary

Problems solved by technology

[0004] At present, there have been some studies on the production of levan by microbial fermentation at home and abroad, but the industrial application has not yet been matured.

However, there are few reports on the use of levansucrase to convert sucrose to produce levan, and there are few studies on molecular modification of levansucrase to improve its performance.

The reported levansucrase generally has problems such as low reaction optimum temperature, poor thermal stability, low substrate concentration tolerance or low substrate conversion rate, and quite a few of the reported levansucrase have If the concentration of sucrose substrate exceeds 10%, the conversion rate will drop significantly, which restricts the production and application

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