Method of producing stalk ethanol by means of mixed fermentation of transgenetic yeast

Abstract

The invention discloses a method of producing stalk ethanol by means of mixed fermentation of transgenetic yeast. The transgenetic yeast can respectively degrade cellulose and xylan of stalks to glucose and xylose and ferment glucose and xylose to ethanol without additionally providing cellulase and xylanase. Degradation of cellulose and xylan and fermentation are synchronously carried out. The method disclosed by the invention has the advantages that by means of transgenetic saccharomyces cerevisiae, transgenetic pichia stipitis and transgenetic candida shehatae, synchronous enzyme hydrolysis-fermentation of a stalk cellulose raw material is realized to produce ethanol without additionally adding cellulase and xylanase, thereby greatly lowering the production cost of stalk cellulose ethanol and promoting the progress of replacing petroleum fuel by the stalk cellulose ethanol.

Description

technical field [0001] The invention relates to the fields of fermentation engineering and genetic engineering, especially using transgenic Saccharomyces cerevisiae and transgenic Pichia stipitis and other mixed fermentations to degrade fibrous raw materials such as straw into glucose and xylose and then convert them into ethanol through a synchronous enzymatic hydrolysis-fermentation process According to the method, the recombinant Saccharomyces cerevisiae can secrete three kinds of cellulase, the transgenic Pichia stipitis and the transgenic Candida shohata can secrete three kinds of xylanase, and can produce ethanol by fermenting xylose. Moreover, the above-mentioned strains have been screened and domesticated, and have good tolerance to ethanol, acetic acid, and furfural. Background technique [0002] As fossil fuels turn from shortage to depletion, the energy crisis is a common problem faced by mankind. In June 2006, my country promulgated the "Interim Measures for the...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent application 200880119451.X discloses bacteria capable of simultaneously fermenting glucose, mannose and xylose and a method for producing bioethanol using the bacteria, however, the process cannot Direct use of straw can only use glucose, xylose, and mannose, and the cost of converting straw into glucose is much higher than that of converting glucose into ethanol

[0004] Chinese patent application 201110135607.7 discloses a process for producing ethanol by synchronous saccharification and fermentation using low-temperature cellulase. However, due to the use of cellulase, the production cost is greatly reduced. Moreover, xylose cannot be utilized, resulting in a low conversion rate of straw into ethanol and a lack of market competitiveness

greatly increase the cost of production

[0007] Chinese patent application 201110460248.2 discloses the fermentation method of cellulosic yeast, double strain Saccharomyces cerevisiae composition and cellulosic ethanol. high

Moreover, the Saccharomyces cerevisiae used can only utilize glucose, not xylose, and the overall utilization rate of straw is low

[0008] The inventor's patent ZL200710107687.9 discloses a method for producing cellulosic ethanol using recombinant Saccharomyces cerevisiae. However, this method can only use glucose and cannot Utilizes xylose and, moreover, expresses only one xylanase, thus cannot fully degrade xylan to xylose

These deficiencies limit the competitiveness of the method

[0009] At present, the main problems of the high cost of straw ethanol production are the high production cost of cellulase and xylanase, the lack of utilization of xylose, and the yeast’s effect on straw pretreatment. Toxic substance tolerance is low, and these problems need to be solved in order to significantly reduce production costs and make straw ethanol competitive in the market