US 9,988,649 B2 · Yeast strains engineered to produce ethanol from acetic acid and glycerol

Abstract

The present invention relates to processes for producing ethanol from lignocellulosic hydrolysates comprising hexoses, pentoses and acetic acid, whereby genetically modified yeast cells are use that comprise an exogenous gene encoding an acetaldehyde dehydrogenase and a bacterial gene encoding an enzyme with NAD+-linked glycerol dehydrogenase activity. The process is further characterized in that glycerol is present in or fed into the culture medium, whereby the modified yeast cell ferments the hexoses, pentoses, acetic acid and glycerol to ethanol. The invention further relates to yeast cells for use in such processes. The yeast cells advantageously comprise genetic modifications that improve glycerol utilization such as modifications that increase one or more of dihydroxyacetone kinase activity and transport of glycerol into the cell. The yeast cell further preferably comprises a functional exogenous xylose isomerase gene and/or functional exogenous genes which confer to the cell the ability to convert L-arabinose into D-xylulose 5-phosphate and they may comprise a genetic modification that increase acetyl-CoA synthetase activity.

Claims16

Dependent claims

A Saccharomyces cell which has been genetically modified to comprise:

(a) an exogenous gene encoding an enzyme with acetaldehyde dehydrogenase activity, that confers on the cell the ability to convert acetic acid into ethanol;
and
(b) a bacterial gene encoding an enzyme with NAD+-linked glycerol dehydrogenase activity (EC 1.1.1.6),
wherein the Saccharomyces cell does not comprise a genetic modification that reduces specific NAD+-dependent formate dehydrogenase activity in the cell, wherein the exogenous gene encoding the enzyme with acetaldehyde dehydrogenase activity comprises a nucleotide sequence encoding the amino acid sequence of:
(i) SEQ ID NO:1, and/or
(ii) SEQ ID NO:3, and/or
(iii) SEQ ID NO:5;
and/or a variant thereof,
wherein the variant of (i), (ii), and/or (iii) is an enzyme in Tables 1, 2, and 3, respectively is 85% identical to SEQ ID NO:1, and/or SEQ ID NO:2, and/or (iii) SEQ ID NO:5, and
wherein the bacterial gene encoding the enzyme with NAD+-linked glycerol dehydrogenase activity comprises a nucleotide sequence encoding an amino acid sequence with at least 90% amino acid sequence identity to SEQ ID NO:7.

7 more elements

Dependencies are inferred from the claim text.

Yeast strains engineered to produce ethanol from acetic acid and glycerol

Life of this patent

Yeast strains engineered to produce ethanol from acetic acid and glycerol

Life of this patent

Abstract

Claims16