Mutant Pul 324 of pullulanibacillus naganoensis pullulanase and use thereof

Abstract

The invention discloses a mutant Pul 324 of a pullulanibacillus naganoensis pullulanase and a use thereof. Based on a modern enzyme engineering technology, an amino acid sequence of a pullulanibacillus naganoensis pullulanase is subjected to molecular modification. Through a PCR method, front 108 amino acid residues of a raw enzyme are deleted so that the mutant Pul 324 which can realize effective secretory expression in escherichia coli hosts is obtained. The mutant Pul 324 is inserted into pET-22b(+) so that a recombinant vector is constructed. The recombinant vector is introduced into an escherichia coli host for secretory expression of the mutant Pul 324. The mutant Pul 324 gene is smaller than a wild type gene and is conducive to plasmid stabilization. Compared with a raw enzyme, themutant Pul 324 can realize effective secretory expression in escherichia coli hosts, realize a fermentation supernatant enzyme activity improved by 24 times and realize an endoenzyme activity improved by 40%. The mutant Pul 324 can improve a pullulanase secretory expression level of a host. An expression product can improve starch hydrolysis efficiency.

Description

technical field [0001] The invention relates to the field of biological technology, in particular to a pullulanase mutant Pul324 of Bacillus nagano and application thereof. Background technique [0002] Starch raw materials generally contain 60-90% amylopectin, and 4-6% glucose residues contained in amylopectin are linked by α-1,6-glycosidic bonds. Pullulanase (Pullulanase, EC 3.2.1.41) is a debranching enzyme that can specifically cut the α-1,6-glucosidic bond of the branch point of amylopectin, thereby cutting off the entire side branch to form amylose. It has considerable value in improving the effect of amylase on starch, increasing the utilization rate of starch, reducing grain consumption, improving product quality and developing new products. It has very important uses in food, medicine, textile, bio-energy and other industries. And good market prospects, for example, it can be used to produce high-purity glucose and fructose, high maltose syrup, fuel ethanol, and mo...

AI Technical Summary

Problems solved by technology

Therefore, there is a big gap between my country and developed countries in the research of pullulanase. The industrial pullulanase is completely dependent on imports, and the pricing power is in the hands of a few foreign companies. The monopolized market supply has led to the high price of domestic pullulanase. The sales price greatly limits the development of domestic related industries

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