Method for producing fuel ethanol by using regrouping zymomonas mobilis to ferment xylose

Abstract

The invention discloses a method for producing fuel ethanol by using regrouping zymomonas mobilis to ferment xylose. The method comprises the following steps of: A), inoculating the regrouping zymomonas mobilis into 100mL of T liquid nutrient solution (containing 10g / L of yeast extract, 2g / L of KH2PO4, 1g / L of MgSO4.7H2O1, 1g / L of (NH4)2SO4 and 20g / L of xylose) according to the inoculum size of 1 percent (v / v), wherein the nutrient solution contains 30 to 50 mu g.mL-1 of kanamycin or ampicillin, standing at the temperature of 20 to 30 DEG C to culture until the OD600 is equal to 1.0, centrifuging the nutrient solution for 5 to 10 minutes under the condition of 8,000 to 1,000rpm, and obtaining the supernatant; and B), accurately measuring 20ml of fermentation liquor, adding the fermentation liquor into a flask with a round bottom, after adding 20ml of water into the fermentation liquor, placing the fermentation liquor in a distilling apparatus, collecting 20ml of distillate, and measuring the concentration of ethanol by gas chromatography.

Description

technical field [0001] The invention belongs to the technical field of bioengineering, and relates to a method for producing fuel ethanol by fermenting xylose, in particular to a method for producing fuel ethanol by fermenting xylose with recombinant Zymomonas mobilis. Background technique [0002] Lignocellulose is a complex of heterogeneously polymerized sugars and lignin, the main components of which are cellulose, hemicellulose and lignin. The respective proportions of the three vary with different parts of the plant. The approximate proportions are: cellulose accounts for 40-50%, hemicellulose accounts for 25-30%, and lignin accounts for 10-20% (Nancy H, et al, 1998). Among them, 85-90% of natural hemicellulose hydrolyzate is xylose. If xylose in plant cellulose can also be fermented to produce ethanol, the yield of ethanol fermentation of lignocellulosic raw materials can be increased by 25% on the original basis. . Therefore, whether xylose is efficiently utilized ...

AI Technical Summary

Problems solved by technology

[0006] The overall idea of ​​transforming Z. mobilis so that it can ferment xylose is to efficiently express four genes related to xylose metabolism in Zymomonas mobilis: sugar isomerase gene (xylA) and xylulokinase gene (xylB ) is responsible for converting xylose into an important intermediate of the pentose phosphate pathway—xylulose-5-phosphate, and the transketolase gene (tktA) and transaldolase gene (talB) are responsible for converting xylulose-5-phosphate Phosphoric acid is converted into an intermediate of the ED pathway through the pentose phosphate pathway, and then enters the ED pathway to generate pyruvate. The conversion steps are lengthy, and many genes are involved, resulting in low efficiency of fermenting xylose to produce ethanol