CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2018-0136647 filed on Nov. 8, 2018 and Korean Patent Application No. 10-2019-0061921, filed on May 27, 2019, and all the benefits accruing therefrom under 35 U.S.C. .sctn.119, the contents of which in its entirety are herein incorporated by reference.

REFERENCE TO SEQUENCE LISTING SUBMITTED VIA EFS-WEB

This application includes an electronically submitted sequence listing in .txt format. The .txt file contains a sequence listing entitled “5398-0122PUS1_ST25.txt” created on Oct. 22, 2019 and is 100,327 bytes in size. The sequence listing contained in this .txt file is part of the specification and is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

This specification relates to a yeast strain capable of simultaneously converting glucose and xylose and a method for producing a biofuel and biomaterial using the same.

Description of the Related Art

New technology for producing biofuel/materials using lignocellulosic biomass have been developed as a method for producing economical fuels/materials that are sustainable in preparation for the post-fossil fuel era. The lignocellulosic biomass is the most abundant carbon source as it accounts for more than 90% of the total biomass produced on earth, is an eco-friendly renewable source, and includes herbaceous and woody biomass. Lignocellulosic biomass includes wood waste, agricultural and forestry waste, bioenergy crops, etc. Production of biofuels using the lignocellulosic biomass leads a great reduction in carbon consumption compared to the fossil fuels and first-generation biofuels.

Biological production technology of biofuels/materials using microorganism fermentation process is economical and eco-friendly, and thus is advantageous. The bioethanol-producing process usingSaccharomyces cerevisiae, a yeast strain, is operated all over the world. In order to more increase the economics and sustainability of such bioethanol, a process for producing a fuel/material using inedible biomass such as lignocellulosic biomass has been suggested, butSaccharomyces cerevisiaehas reduced conversion efficiency as it uses biomass-derived hexose (representatively glucose; 50% of the biomass at maximum) only but not pentose (representatively xylose; 25% of the biomass at maximum). If the problem is overcome, a maximum biomass conversion rate is expected to increase up to 50% to 75%. In this regard, the development of xylose converting-strain is underway.

Such yeast strain does not endogenously possess a xylose metabolic pathway, and thus is incapable of xylose metabolism. There has been a report that a transformed strain in which an oxidoreductase based-xylose metabolic pathway has been developed to provide the yeast with xylose utilization capacity. However, the xylose utilization capacity has not reached a satisfactory level. In particular, the oxidoreductase based-xylose metabolic pathway has a problem in that ethanol production yield is low due to cofactor imbalance. Further, when glucose and xylose, which are main carbon sources derived from lignocellulosic biomass, are simultaneously present, xylose utilization capacity rapidly decreases, and xylose is consumed only after all glucose is consumed, thereby causing a problem of reduced productivity. There is a limitation on an additional modification of xylose-utilizing strains that have so far been developed, thus limiting the product to bioethanol.

CITATION LIST

Patent Literature

Non-Patent Literature 1: Sun-Mi Lee et al., Systematic and evolutionary engineering of xylose isomerase-based pathway inSaccharomyces cerevisiaefor efficient conversion yields, Biotechnol. Biofuel., 2014 1:122

Non-Patent Literature 2: Verhoeven M D et al., Mutations in PMR1 stimulate xylose isomerase activity and anaerobic growth on xylose of engineeredSaccharomyces cerevisiaeby influencing manganese homeostasis, Sci. Rep. 2017 7:46155

SUMMARY OF THE INVENTION

Technical Problem

In an aspect, the technical problem of the present invention is to provide a transformed yeast strain capable of co-converting glucose/xylose and having enhanced xylose utilization capacity.

In an aspect, the technical problem of the present invention is to provide a method for preparing a transformed yeast strain capable of co-converting glucose/xylose and having enhanced xylose utilization capacity.

In an aspect, the technical problem of the present invention is to provide a method for producing biofuels and biomaterials using a transformed yeast strain capable of co-converting glucose/xylose and having enhanced xylose utilization capacity.

Technical Solution

To solve the problems, an exemplary embodiment of the present invention provides a transformed yeast strain ofSaccharomyces cerevisiae, comprising at least one of a mutation or deletion of PMR1 represented by the base sequence of SEQ ID NO: 1 and a mutation or deletion of ASC1 represented by the base sequence of SEQ ID NO: 3; and

a gene encoding a xylose isomerase; and at least one of a gene encoding a xylulokinase and a gene encoding a transaldolase,

wherein the mutation of PMR1 represented by the base sequence of SEQ ID NO: 1 is a mutation to PMR1G681Arepresented by the base sequence of SEQ ID NO: 2; and

the mutation of ASC1 represented by the base sequence of SEQ ID NO: 3 is a mutation to ASC1Q237*represented by the base sequence of SEQ ID NO: 4.

To solve the problems, an exemplary embodiment of the present invention provides a method for preparing the transformed yeast strain, comprising inserting a gene encoding a xylose isomerase; and at least one of a gene encoding a xylulokinase and a gene encoding a transaldolase; and

performing at least one of a mutation or deletion of PMR1 represented by the base sequence of SEQ ID NO: 1 and a mutation or deletion of ASC1 represented by the base sequence of SEQ ID NO: 3,

while havingSaccharomyces cerevisiaeas a parent strain,

wherein the mutation of PMR1 or ASC1 comprises adaptive evolution by subculturing the strain in a minimal medium containing xylose as a sole carbon source.

To solve the problems, an exemplary embodiment of the present invention provides a method for producing a biofuel and biomaterial, comprising fermenting the transformed yeast strain by culturing the transformed yeast strain in a medium containing xylose or glucose as a sole carbon source or a medium containing glucose and xylose as mixed carbon sources.

