Propagation method of novel yeast for metabolism of pentose and hexose by co-fermentation

Abstract

A propagation method of novel yeast for metabolism of pentose and hexose by co-fermentation is disclosed. By the use of traditional yeast for production of cellulosic ethanol for metabolism of pentose, residual sugar content of pentose in metabolism terminal is high and yield of ethanol is low. Traditional alcohol yeast can only metabolize glucose but cannot metabolize xylose generated by enzyme hydrolysis of straw for production of alcohol and has low alcohol production capacity. The propagation method of novel yeast for metabolism of pentose and hexose co-fermentation involves wine-brewing high activity yeast. The propagation method of the wine-brewing high activity yeast for metabolism of pentose and hexose by co-fermentation comprises the following steps: (1) test-tube yeast propagation; (2) primary cultivation; and (3) secondary cultivation. The application of the invention relates to the field of biological fermentation, especially to the propagation method of novel yeast for metabolism of pentose and hexose by co-fermentation.

Description

[0001] Technical field: [0002] The invention relates to the field of biological fermentation, in particular to a method for expanding the capacity of a novel co-fermentation yeast that metabolizes five and six carbon sugars. [0003] Background technique: [0004] In the process of producing ethanol from lignocellulose, the weak acids (mainly acetic acid), furfural, 5-hydroxymethylfurfural and aromatic compounds produced in the pretreatment process will inhibit the production of yeast species in the enzymolysis solution after treatment. Growth and fermentation lead to a decline in ethanol production capacity. If the material after the steam explosion is washed and detoxified, not only the water consumption is large, but also the water washing filtration and compression equipment need to be integrated in the production process, which will further increase the production cost and fermentation. The complexity of the process, in addition, the yeast strains have a low utilization ...

AI Technical Summary

Problems solved by technology

[0004] In the process of producing ethanol from lignocellulose, the weak acids (mainly acetic acid), furfural, 5-hydroxymethylfurfural and aromatic compounds produced in the pretreatment process will inhibit the production of yeast species in the enzymolysis solution after treatment. Growth and fermentation lead to a decline in ethanol production capacity. If the material after the steam explosion is washed and detoxified, not only the water consumption is large, but also the water washing filtration and compression equipment need to be integrated in the production process, which will further increase the production cost and fermentation. The complexity of the process, in addition, the yeast strains have a low utilization rate of the five-carbon sugar converted from hemicellulose in the production raw materials. Therefore, the directional domestication of the yeast is used to increase the ethanol production of the yeast (including the utilization of the five-carbon sugar ) and inhibitor tolerance, it is of great significance to directly ferment the enzymatic hydrolyzate in the hot water environment without water washing and detoxification to produce ethanol; in the fermentation process of the existing bioethanol production process, dry yeast is used to cultivate After the base is activated, the expanded culture is carried out. After the expanded culture, the yeast is divided, and a small part (20-30%) is used as seeds to continue the expanded culture, and most (70-80%) are inserted into the fermented sugar solution for fermentation; Commercial alcoholic yeast basically does not metabolize five-carbon sugars, and cannot adapt to the high five-carbon sugars in the raw material sugar liquid of cellulosic ethanol. Using traditional yeast to produce cellulosic ethanol metabolizes terminal five-carbon sugars with extremely high residual sugar and low ethanol yield ;Traditional yeasts have poor tolerance to the inhibitors produced in the straw pretreatment process, resulting in difficulty in yeast value-added, high mortality, and high residual sugar in alcoholic fermentation; enzymatic sugar solution needs to be detoxified, which increases the complexity of the production process , but also increase production costs; traditional alcoholic yeast can only metabolize glucose, but cannot metabolize xylose produced by enzymatic hydrolysis of straw to produce alcohol, and the alcohol production capacity is low

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