MODULATION OF FORMATE OXIDATION BY RECOMBINANT YEAST HOST CELL DURING FERMENTATION
The present disclosure concerns recombinant yeast host cells having a first genetic modification for increasing formate production, when compared to a corresponding native yeast host cell as well as a source of formate dehydrogenase activity. The source of formate can be an internal source of formate dehydrogenase activity and/or the recombinant yeast host call can be supplemented by an external source of formate dehydrogenase activity.
1 . A recombinant yeast host cell having (i) a first genetic modification for increasing formate production, when compared to a corresponding native yeast host cell and (ii) a source of formate dehydrogenase activity, wherein the source of formate dehydrogenase activity is:
an internal source of formate dehydrogenase activity provided by a second genetic modification; and/or
an external source of formate dehydrogenase activity provided by a further yeast host cell having a third genetic modification.
2 . The recombinant yeast host cell of claim 1 , wherein the first genetic modification comprises introducing one or more first heterologous nucleic acid molecule encoding one or more polypeptide having pyruvate formate lyase activity in the recombinant yeast host cell.
3 . The recombinant yeast host cell of claim 2 , wherein the one or more polypeptide having pyruvate formate lyase activity comprises PFLA, PFLB or a combination thereof.
4 . The recombinant yeast host cell of claim 2 or 3 , wherein the one or more polypeptide having pyruvate formate lyase activity is from Bifidobacterium sp.
5 . The recombinant yeast host cell of claim 4 , wherein the one or more polypeptide having pyruvate formate lyase activity is from Bifidobacterium adolescentis.
6 . The recombinant yeast host cell of claim 5 , wherein the one or more polypeptide having pyruvate formate lyase activity comprises the amino acid sequence of SEQ ID NO: 6, is a variant of the amino acid sequence of SEQ ID NO: 6 having pyruvate formate lyase activity or is a fragment of the amino acid sequence of SEQ ID NO: 6 having pyruvate formate lyase activity.
7 . The recombinant yeast host cell of claim 5 or 6 , wherein the one or more polypeptide having pyruvate formate lyase activity comprises the amino acid sequence of SEQ ID NO: 7, is a variant of the amino acid sequence of SEQ ID NO: 7 having pyruvate formate lyase activity or is a fragment of the amino acid sequence of SEQ ID NO: 7 having pyruvate formate lyase activity.
8 . The recombinant yeast host cell of any one of claims 1 to 7 , wherein the second and/or third genetic modification comprises introducing a second or third heterologous nucleic acid molecule encoding a polypeptide having formate dehydrogenase activity.
9 . The recombinant host cell of claim 8 , wherein the polypeptide having formate dehydrogenase activity is FDH1.
10 . The recombinant yeast host cell of claim 8 or 9 , wherein the polypeptide having formate dehydrogenase activity uses NAD + as a primary cofactor.
11 . The recombinant yeast host cell of claim 10 , wherein the polypeptide having formate dehydrogenase activity has the amino acid sequence of SEQ ID NO: 1 or 5, is a variant of the amino acid sequence of SEQ ID NO: 1 or 5 having formate dehydrogenase activity or is a fragment of the amino acid sequence of SEQ ID NO: 1 or 5 having formate dehydrogenase activity.
12 . The recombinant yeast host cell of claim 8 or 9 , wherein the polypeptide having formate dehydrogenase activity uses NADP + as a primary cofactor.
13 . The recombinant yeast host cell of claim 12 , wherein the polypeptide having formate dehydrogenase activity has the amino acid sequence of SEQ ID NO: 2, 3, 4, 21, 23, 25, 26 or 27, is a variant of the amino acid sequence of SEQ ID NO: 2, 3, 4, 21, 23, 25, 26 or 27 having formate dehydrogenase activity or is a fragment of the amino acid sequence of SEQ ID NO: 2, 3, 4, 21, 23, 25, 26 or 27 having formate dehydrogenase activity.
14 . The recombinant yeast host cell of any one of claims 8 to 13 , wherein the second and/or third heterologous nucleic acid molecule further comprises a mitochondrial target sequence operatively associated with the nucleic acid sequence encoding the polypeptide having formate dehydrogenase activity.
15 . The recombinant yeast host cell of claim 14 , wherein the mitochondrial target sequence is from the CYB2 gene.
16 . The recombinant yeast host cell of claim 15 , wherein the mitochondrial target sequence has the amino acid sequence of SEQ ID NO: 11, is a variant of the amino acid sequence of SEQ ID NO: 11 or is a fragment of the amino acid sequence of SEQ ID NO: 11.
17 . The recombinant yeast host cell of any one of claims 8 to 16 , wherein the second and/or third heterologous nucleic acid molecule further comprises a promoter operatively associated with the nucleic acid sequence encoding the polypeptide having formate dehydrogenase activity.
18 . The recombinant yeast host cell of claim 17 , wherein the promoter comprises at least one of tef2p, ssa1p, adh1p, cdc19p, tpi1p, cyc1p, pgk1p, tdh2p, eno2p, hxt3p, qcr8p, tdh1p, tdh3p or hor7p.
19 . The recombinant yeast host cell of any one of claims 1 to 18 expressing native FDH gene(s).
20 . The recombinant yeast host cell of any one of claims 1 to 19 , wherein the further yeast host cell expresses native FDH gene(s).
21 . The recombinant yeast host cell of any one of claims 1 to 18 comprising a fourth genetic modification for invactivating of at least one of the native FDH gene(s).
22 . The recombinant yeast host cell of any one of claims 1 to 18 and 21 , wherein the further yeast host cell comprises a fifth genetic modification for invactivating of at least one of the native FDH gene(s).
23 . The recombinant yeast host cell of claim 19 to 22 , wherein the native FDH gene(s) comprises FDH1, FDH2 or both.
24 . The recombinant yeast host cell of any one of claims 1 to 23 being from the genus Saccharomyces.
25 . The recombinant yeast host cell of any one of claims 1 to 24 , wherein the further yeast host cell is from the genus Saccharomyces.
26 . The recombinant yeast host cell of claim 24 or 25 being from the species Saccharomyces cerevisiae.
27 . The recombinant yeast host cell of any one of claims 24 to 26 , wherein the further yeast host cell is from the species Saccharomyces cerevisiae.
28 . A combination for fermenting a biomass, the combination comprising the recombinant yeast host cell defined in any one of claims 1 to 27 and the further yeast host cell defined in any one of claims 1 to 27 .
29 . The combination of claim 28 , wherein at least one of the recombinant yeast host cell or the further yeast host cell is provided as a cream.
30 . A process for converting a biomass into a fermentation product, the process comprises contacting the biomass with the recombinant yeast host cell defined in any one of claims 1 to 27 , optionally in combination with the further yeast host cell defined in any one of claims 1 to 27 , or the combination of claim 28 or 29 under condition to allow the conversion of at least a part of the biomass into the fermentation product.
31 . The process of claim 30 , wherein the biomass comprises corn.
32 . The process of claim 31 , wherein the corn is provided as a mash.
33 . The process of any one of claims 30 to 32 , wherein the fermentation product is ethanol.
34 . The process of any one of claims 30 to 33 being conducted, at least in part, in the presence of a stressor.
35 . The process of claim 34 , wherein the stressor in lactic acid, formic acid and/or a bacterial contamination.