Brewing yeast strain capable of metabolizing xylose

Abstract

The invention discloses a brewing yeast strain capable of metabolizing xylose. The strain is a brewing yeast (Saccharomyces cerevisiae) BSHH02B, and is preserved in the China General Microbiological Culture Collection Center (CGMCC) on Feb. 8th, 2012, wherein the preservation number is CGMCC No. 5747. The strain carries a unique xylose metabolizing way, i.e. a molecular xylose generates a molecular pyruvic acid and a molecular glycolaldehyde through two mesostate, i.e. xylonic acid and 3-deoxyl-D-glycerol-ketopentose acid. By the xylose metabolizing way, the brewing yeast BSHH02B can quickly grow by using the xylose under an aerobic condition, and can be applied to the production of chemical products by using xylose-containing raw materials, wherein the chemical products include ethanol, glycol, carboxylic acid and the like.

Description

technical field [0001] The invention relates to a strain of Saccharomyces cerevisiae engineered strain, in particular to a strain of Saccharomyces cerevisiae engineered strain which has built an exogenous xylose metabolism pathway and can rapidly metabolize xylose. Background technique [0002] The development and stockpiling of alternative petroleum-based fuel and chemical production technologies are necessary for social development and national security. The huge annual output of lignocellulosic raw materials can provide a material basis for the production of large-scale bio-based related products, so it has attracted much attention. The main components of available sugars in lignocellulose are glucose and xylose. Since glucose is an easy-to-use sugar, the conversion of xylose, which can be as high as 30% but is not easy to use, is the key to fully utilizing raw materials and is also the key to reducing bio-based sugars. The basis of chemical production costs. At present...

AI Technical Summary

Problems solved by technology

The path is cumbersome and inefficient

First, there are limitations in the establishment of the two pathways for the conversion of xylose to xylulose in Saccharomyces cerevisiae

① The pathway catalyzed by xylose reductase (XR) and xylitol dehydrogenase (XDH) is uncoupled due to the uncoupling of XR and XDH cofactors, resulting in redox imbalance when the strain introduced into this pathway metabolizes xylose, resulting in side effects The problem of product xylitol accumulation has not been completely solved; ② Although the xylose isomerase (XI) pathway can avoid the problem of redox imbalance, there are only a few xylose isomerases in Saccharomyces cerevisiae Active expression is achieved in the medium, and the enzyme activity is not high at the growth temperature of Saccharomyces cerevisiae (about 30°C), resulting in insufficient conversion efficiency of xylose during fermentation

Secondly, xylulose needs to be phosphorylated into xylulose-5-phosphate to enter the pentose phosphate pathway. Controlling the expression level of xylulokinase (XK) that catalyzes this reaction becomes another bottleneck. Studies have shown that XK enzyme activity is low It shows that the efficiency of xylose metabolism is insufficient, and the high enzyme activity affects cell growth due to excessive consumption of ATP

Finally, xylulose-5-phosphate needs to go through the pentose phosphate pathway and then enter the glycolysis pathway to be converted into pyruvate. The main function of the pentose phosphate pathway is to provide intermediate products for the synthesis of many macromolecules (such as nucleic acids) in the cell , it is conceivable that the conversion efficiency of PPP is difficult to meet the metabolite flux required for efficient xylose catabolism on the basis of ensuring the synthesis of its own macromolecules

Images