High-temperature acid-resistant alpha-amylase mutant strain and construction method thereof

Abstract

The invention relates to a mutant strain of a high temperature acid-proof Alpha-amylase and a method for producing the mutant strain. The high temperature acid-proof Alpha-amylase gene is obtained by mutating the Bacillus licheniformis high-temperature resistant Alpha-amylase gene (Leu134 Arg and Ser320 Ala); the high temperature acid-proof Alpha-amylase gene is integrated into the genom DNA of the parent strain Bacillus licheniformis by establishing a target carrier and by adopting the method of homologous recombination so that the Bacillus licheniformis mutate strain is obtained to realize the homology effective expression of the high temperature acid-proof Alpha-amylase gene. The Alpha-amylase produced by the mutate strain is resistant to high temperature and has the acid stability improved evidently, thereby providing good technique condition for the starch deep processing industry such as alcohol and mashing in China, lowering the cost, saving the energy and the industrial grain, and satisfying the requirements of the starch raw material liquefying technique on acid conditions.

Description

technical field [0001] The invention relates to the field of bioengineering, in particular to a mutant strain of high-temperature acid-resistant alpha-amylase and a construction method thereof. Background technique [0002] α-amylase (α-1,4-glucan-glucanhydrolase EC 3.2.1.1), also known as liquefied amylase, can cut the α-1,4 bond arbitrarily from the inside of the starch molecule to produce maltose with a relatively small molecular weight dextrin. Under the action of α-amylase, the starch molecules degrade rapidly, the viscosity decreases, and the liquefaction is completed. α-amylase has considerable commercial value and is widely used in starch deep processing industry, alcohol industry, beer industry, citric acid industry, monosodium glutamate and starch saccharification industry, pharmaceutical industry and textile industry. α-amylase can be produced by microbial fermentation, and can also be extracted from plants and animals. At present, most of the industrial produc...

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Problems solved by technology

[0007] It can be seen that the optimum temperature of acid α-amylase in China is lower than 70°C at present. Because the enzyme activity will be greatly lost when the hydrolysis reaction exceeds 70°C, it cannot adapt to the starch deep processing industries such as alcohol and starch saccharification in my country. Require

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