Mutant yeast strain with decreased glycerol production

Patent metadata

Field	Value
Publication number	US-9850502-B2
Application number	US-201314431225-A
Country	US
Kind code	B2
Filing date	Sep 23, 2013
Priority date	Sep 25, 2012
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

The disclosure relates to the use of a mutant SSK1 gene encoding a truncated ssk1 protein for the construction of a mutant yeast strain with decreased glycerol production, when compared to the wild-type strain. It relates further to the use of such strains for high-yield bioethanol production, especially in high osmotic media, or on cellulosic hydrolysates, where normal yeast strains do produce a significant amount of glycerol.

First claim

The invention claimed is:

1. A method of producing bioethanol, the method comprising:
utilizing a Saccharomyces spp. yeast strain for high yield bioethanol production by culturing the Saccharomyces spp. yeast strain in a medium,
wherein the Saccharomyces spp. yeast strain comprises a gene encoding a truncated ssk1 protein,
wherein the truncated ssk1 protein lacks the response regulator receiver domain,
wherein the truncated ssk1 protein comprises at least amino acids 1-300 of SEQ ID NO: 2, and
wherein the yeast strain lacks a gene encoding a wild-type ssk1 protein.

2. The method of according to claim 1 , wherein the truncated ssk1 protein further comprises at least amino acids 330-356 of SEQ ID NO: 4.

3. The method according to claim 1 , wherein the truncated ssk1 protein is encoded by a nucleic acid molecule comprising SEQ ID NO:3.

4. The method according to claim 1 ,
wherein the yeast strain strain is a diploid, polyploid, or aneuploid strain, and
wherein all wild-type copies of SSK1 gene have been replaced by a gene encoding the truncated ssk1 protein.

5. The method according to claim 1 , wherein the yeast strain further comprises a specific allele encoding a protein selected from the group consisting of gpd1 L164P , hot1 P107S,H274Y and smp1 R110Q,P269Q .

6. The method according to claim 1 , wherein the bioethanol is produced in high osmotic media or on cellulosic hydrolysates.

7. The method according to claim 1 , having a glycerol over ethanol ratio lower than 4%.

8. A method of producing ethanol of the type involving culturing a Saccharomyces spp. yeast strain that co-produces glycerol with the ethanol, wherein the improvement comprises:
culturing a recombinant Saccharomyces spp. yeast strain comprising a gene encoding a truncated ssk1 protein lacking the response regulator receiver domain and comprising at least amino acids 1-300 of SEQ ID NO: 2, wherein the Saccharomyces spp. yeast strain lacks a gene encoding a wild-type ssk1 protein,
so as to decrease glycerol production when compared to wild-type Saccharomyces spp. yeast strain.

9. The method according to claim 8 , wherein the ethanol is produced on cellulosic hydrolysates.

10. The method according to claim 8 , wherein glycerol production is less than 0.06 g g −1 , when tested on minimal medium with 5% glucose.

Assignees

• Vib Vzw
• Univ Leuven Kath
• Univ Leuven Kath

Inventors

• Thevelein Johan
• Foulquie-Moreno Maria Remedios
• Hubmann Georg

Classifications

• C07K14/395

  from Saccharomyces · CPC title

• C12Q1/6895

  for plants, fungi or algae · CPC title

• C12Q2600/158

  Expression markers · CPC title

• C07K14/39

  from yeasts · CPC title

• C12P7/06 Primary

  Ethanol, i.e. non-beverage · CPC title