Saccharomyces cerevisiae engineering bacterial strain capable of efficiently using lactose to produce fuel ethanol

Abstract

The invention discloses a saccharomyces cerevisiae engineering bacterial strain capable of efficiently using lactose to produce fuel ethanol. According to the saccharomyces cerevisiae provided by the invention, a saccharomyces cerevisiae engineering bacterium (Saccharomyces cerevisiae AY5-10B24M) is obtained by selecting a strong promoter PGK1 to respectively express a lactose lytic enzyme gene LAC4 and a lactose permease gene LAC12, knocking to remove metal-inert gas welding (MIG1) and NTH1 gens simultaneously, and releasing a glucose repression phenomenon, wherein the saccharomyces cerevisiae engineering bacterium has high tolerance and is capable of efficiently using lactose to produce fuel ethanol, and the preservation number of the strain is CGMCC (China General Microbiological Culture Collection Center) No. 5843. Under the condition that the fermenting performance of the bacterium is not affected, compared with a receptor strain (Saccharomyces cerevisiae CGMCC No2.1364), the bacterium can grow and be fermented in a culture medium of which the whey concentration is 100g / L (the content of lactose is about 50g / L) to produce ethanol, wherein the fermentation period is 120 hours, the utilization rate of the lactose in whey is 97.65 percent; and the yield of absolute ethyl alcohol to the lactose is 46.4 percent (which is equivalent to 86.24 percent of a theoretic yield). The repression of glucose to galactose is relieved at the same time, and the glucose and the galactose can be utilized at the same time. The saccharomyces cerevisiae engineering bacterial strain can be normally fermented in ethanol solution of which the concentration of ethanol is 19 percent (v / v), or at the environmental temperature of 39 DEG C.

Description

technical field [0001] The invention belongs to the technical field of bioengineering, and relates to the breeding of industrial microorganisms, in particular to a strain of Saccharomyces cerevisiae engineering bacteria that can alleviate glucose repression and improve stress resistance and utilize lactose efficiently. Background technique [0002] Whey refers to the extremely thin liquid left after the flocs are separated when making cheese or casein. It is a by-product of industrial production of cheese and casein. Every 1 ton of cheese produced produces 9 tons of whey, which contains 55% of milk However, because whey has high BOD (biological oxygen demand) and COD (chemical oxygen demand), it causes a great burden on the environment. At present, the global whey production is about 1.6 billion tons, and only 50% of it is processed for food, feed, etc. The remaining about 800 million tons are not effectively utilized and are excreted into nature, which not only causes envir...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to solve the problem that wild-type Saccharomyces cerevisiae cannot use lactose as the sole carbon source, but the genetically engineered Saccharomyces cerevisiae has growth inhibition and low stress resistance, and provides a Saccharomyces cerevisiae strain that can efficiently utilize lactose to produce fuel ethanol Yeast engineered strain

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