Yeast expressing heterologous glucoamylase

1. A recombinant yeast host cell for saccharification and fermentation of a biomass, the recombinant yeast host cell having a heterologous nucleic acid molecule encoding a heterologous polypeptide having glucoamylase activity, wherein the heterologous nucleic acid molecule comprises:

a first polynucleotide encoding a heterologous signal sequence wherein the heterologous signal sequence has the amino acid sequence of SEQ ID NO: 5; and

a second polynucleotide encoding the heterologous polypeptide having glucoamylase activity, wherein the polypeptide having glucoamylase activity has the amino acid sequence of SEQ ID NO: 3 or 13, is a variant having at least 90% identity with the amino acid sequence of SEQ ID NO: 3 or 13 and having glucoamylase activity, or is a fragment having at least 90% identity with the amino acid sequence of SEQ ID NO: 3 or 13 and having glucoamylase activity;

wherein the first polynucleotide molecule is operatively associated with the second polynucleotide molecule.

2. The recombinant yeast host cell of claim 1 , wherein the heterologous nucleic acid molecule encodes the heterologous polypeptide having the amino acid sequence of SEQ ID NO: 1 or 11, a variant having at least 90% identity with the amino acid sequence of SEQ ID NO: 1 or 11 and having glucoamylase activity, or a fragment having at least 90% identity with the amino acid sequence of SEQ ID NO: 1 or 11 and having glucoamylase activity.

3. The recombinant yeast host cell of claim 1 , wherein the heterologous nucleic acid molecule further comprises a third polynucleotide comprising a heterologous promoter operatively associated with the first polynucleotide and the second polynucleotide allowing the expression of the heterologous polypeptide having glucoamylase activity.

4. The recombinant yeast host cell of claim 3 , wherein the heterologous promoter is capable of allowing the expression of the heterologous polypeptide having glucoamylase activity during propagation.

5. The recombinant yeast host cell of claim 1 , wherein the heterologous polypeptide having glucoamylase activity is a secreted polypeptide.

6. The recombinant yeast host cell of claim 1 , wherein the heterologous polypeptide having glucoamylase activity is a membrane-associated polypeptide.

7. The recombinant yeast host cell of claim 6 , wherein the membrane-associated polypeptide is a tethered polypeptide.

8. The recombinant yeast host cell of claim 1 comprising a further heterologous nucleic acid molecule encoding a heterologous alpha-amylase and/or a heterologous glucoamylase.

9. The recombinant yeast host cell of claim 8 , wherein the heterologous alpha-amylase has the amino acid sequence of any one of SEQ ID NO: 17 to 26, is a variant having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 17 to 26 and having alpha-amylase activity or is a fragment having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 17 to 26 and having alpha-amylase activity.

10. The recombinant yeast host cell of claim 8 , wherein the heterologous glucoamylase has the amino acid sequence of any one of SEQ ID NO: 27 to 36, a variant having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 27 to 36 and having glucoamylase activity or a fragment having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 27 to 36 and having glucoamylase activity.

11. The recombinant yeast host cell of claim 1 , wherein the recombinant yeast host cell is from the genus Saccharomyces.

12. The recombinant yeast host cell of claim 11 , wherein the recombinant yeast host cell is from the species Saccharomyces cerevisiae.

13. A composition comprising the recombinant yeast host cell of claim 1 and starch.

14. A process for saccharification and fermentation of a biomass into a fermentation product, the process comprises contacting the biomass with the recombinant yeast host cell defined in claim 1 , under a condition that allows the conversion of at least a part of the biomass into the fermentation product.

15. The process of claim 14 , wherein the biomass is derived from or comprises corn, potato, cassava, rice, wheat, lignocellulosic material, milo or buckwheat.

16. The process of claim 15 , wherein the biomass is derived from or comprises corn.

17. The process of claim 16 , wherein the biomass comprises or is corn mash.

18. The process of claim 14 , wherein the fermentation product is ethanol.

19. The process of claim 14 , wherein the fermentation is conducted in the presence of a stressor.

20. The process of claim 19 , wherein the stressor is low pH.

21. The process of claim 20 , wherein the stressor is pH of 5.0 or lower.

22. The process of claim 20 , wherein the stressor is pH of 4.0 or lower.

23. The process of claim 19 , wherein the stressor is an elevated temperature.

24. The process of claim 14 comprising including an exogenous enzyme in the biomass.

25. The process of claim 24 , wherein the exogenous enzyme is an alpha-amylase and/or a glucoamylase.

26. The process of claim 25 , wherein the alpha-amylase has the amino acid sequence of any one of SEQ ID NO: 17 to 26, is a variant having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 17 to 26 and having alpha-amylase activity or is a fragment having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 17 to 26 and having alpha-amylase activity.

27. The process of claim 25 , wherein the glucoamylase has the amino acid sequence of any one of SEQ ID NO: 27 to 36, is a variant having at least 90% identity with the amino acid sequence of any one of SEQ ID NO: 27 to 36 having glucoamylase activity or is a fragment of the amino acid sequence of any one of SEQ ID NO: 27 to 36 and having glucoamylase activity.

28. The process of claim 14 avoiding including an exogenous enzyme in the biomass.

29. The process of claim 28 , wherein the exogenous enzyme is a glucoamylase.