Eukaryotic cell and method for producing glycolic acid
The present invention concerns a eukaryotic host selected from microorganisms, and a method for producing glycolic acid using said eukaryotic host cells, especially cells of a genetically modified fungal host. Further this invention relates to a glycolic acid product obtained using the method described here and the use of genetically modified microorganism cells in production of glycolic acid.
1. A eukaryotic production host selected from yeast and filamentous fungus cell of species Saccharomyces cerevisiae, Kluveromyces lactis, Candida krusei and Aspergillus niger , wherein the host:
has been genetically modified by transformation of a protein-encoding polynucleotide into the genome of the host cell,
expresses a heterologous gene encoding the glyoxylate reductase of SEQ ID NO: 3, and
produces glycolic acid at a pH of 1.5 to 6.0,
wherein glyoxylate pathway flux has been increased:
a) by overexpressing one or more of the genes selected from isocitrate lyase, fumarate reductase, aconitase, citrate synthase and acetyl-coenzyme A synthetase; or
b) by reducing activity of the enzymes consuming the intermediates of the cycle; or
c) any combination of a) and b).
2. The host of claim 1 , which is capable of producing glycolic acid in non-buffered culturing conditions.
3. The host of claim 1 , wherein the glyoxylate reductase gene encodes a protein having EC number 1.1.1.79 or 1.1.1.26.
4. The host of claim 3 , wherein the cells of the host comprise the genes encoding proteins of SEQ ID NO: 3.
5. A eukaryotic production host selected from yeast and filamentous fungus cell of species Saccharomyces cerevisiae, Kluveromyces lactis, Candida krusei and Aspergillus niger , wherein the host:
has been genetically modified by transformation of a protein-encoding polynucleotide into the genome of the host cell,
expresses a heterologous gene encoding the glyoxylate reductase of SEQ ID NO: 3, and
produces glycolic acid at a pH of 1.5 to 6.0,
wherein glyoxylate cycle regulating gene REG1 has been attenuated or CAT8 has been activated.
6. A eukaryotic production host selected from yeast and filamentous fungus cell of species Saccharomyces cerevisiae, Kluveromyces lactis, Candida krusei and Aspergillus niger , wherein the host:
has been genetically modified by transformation of a protein-encoding polynucleotide into the genome of the host cell,
expresses a heterologous gene encoding the glyoxylate reductase of SEQ ID NO: 3, and
produces glycolic acid at a pH of 1.5 to 6.0,
wherein alcohol production has been reduced by:
a) overexpressing one or more of pyruvate carboxylases; or
b) reducing expression of gene encoding alcohol dehydrogenase.
7. A eukaryotic production host selected from yeast and filamentous fungus cell of species Saccharomyces cerevisiae, Kluveromyces lactis, Candida krusei and Aspergillus niger , wherein the host:
has been genetically modified by transformation of a protein-encoding polynucleotide into the genome of the host cell,
expresses a heterologous gene encoding the glyoxylate reductase of SEQ ID NO: 3, and
produces glycolic acid at a pH of 1.5 to 6.0,
wherein NADPH availability has been improved by overexpressing cytosolic aldehyde dehydrogenase gene or deleting phosphoglucose isomerase gene.