construction of HD34-1 strain and method for making alcohol-free beer with HD34-1 strain as ferment strain

Abstract

The invention relates to a method of engineered bacterium HD34-1 construction and alcohol free beer brewing using engineered bacterium HD34-1 as zymogen. HD34-1 is constructed as follows: a.designing 5' and 3' primer; b. amplifying ADH gene; c. connecting with expression vector pYC6 / CT; d. transforming Saccharomyces cerevisiae HD34; e. screening transformer to obatain HD34-1 strain. Alcohol free beer brewing method using HD34-1 as zymogen is as follows : a. activating HD34-1; b. switching strain to medium and shaking culture; c. inoculating strain to be amplified in malt juice containing fermenter; d. aerating and fermenting e.determing the sugar degree, and stopping fermentation when sugar degree decrease to 5 DEG BX; f. lowering the temperature. The inventive strain can catalyze positive reaction of primary alcohol with aldehyde, lower ethanol yield and simplify the process.

Description

Technical field: [0001] The invention relates to a method for constructing a genetically engineered strain and a method for brewing non-alcoholic beer, in particular to a method for constructing a genetically engineered strain and a method for brewing non-alcoholic beer using the strain as a fermentation strain. Background technique: [0002] Alcohol dehydrogenase (E.C.1.1.1.1, referred to as ADH) is a broadly specific zinc-containing metalloenzyme (Drewkw et al., 1988), which can use NAD as a coenzyme to catalyze the reversible reaction between primary alcohols and aldehydes. It is an important fermentation enzyme in the beer fermentation process, and its positive reaction catalytic activity is of great significance for reducing the ethanol content in beer. Therefore, this enzyme is a key enzyme for the production of low-alcohol or no-alcohol beer by microbial fermentation. Alcohol-free beer refers to beer with no alcohol or very little alcohol content. Like ordinary beer,...

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Problems solved by technology

However, these existing methods have more or less corresponding problems and disadvantages in technology: 1. Special yeast controls fermentation: because the mash contains a large amount of unfermented maltose, it has a very strong sweet taste, and during the fermentation process Due to the low-alcohol and high-sugar mash environment, the microbial control requirements of the fermented mash are very strict. It must be ensured that there is only one kind of yeast in the mash during the fermentation process, otherwise it will lead to the failure of the fermentation; 2. Interrupted fermentation: due to fermentation Incomplete, its stability is not as good as traditional fermented beer; 3. Low temperature controlled fermentation: In addition to high residual sugar and sweet taste, the post-fermentation stage and freeze filtration stage are very easy to be infected with bacteria, and the process control is relatively strict; 4. "Cold beer "Mix" process, Barrell's patent and high-concentration diluted beer have strict requirements on equipment due to the needs of the process, so it is difficult to apply it on a large scale; Great changes have taken place, resulting in tastes that are not easily accepted by consumers; 6. Vacuum distillation, evaporation, reverse osmosis and dialysis: Although these technologies have solved the problem of beer flavor, but due to the impact of these technologies on equipment, workshops and technical personnel There are very high requirements, and it is not the best choice for manufacturers

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