Process for displacing an exogenous enzyme

A process for fermenting a biomass into ethanol comprising:

• (i) propagating a stabilized liquid yeast dose of between 30 and 210 kg of a recombinant yeast host cell to obtain propagated recombinant yeast host cells;
• (ii) contacting the propagated recombinant yeast host cells with a biomass in a fermentor having a working volume of at least 100,000 gallons, under a condition that allows conversion of at least a part of the biomass into ethanol, wherein:
• the biomass comprises starch or a starch derivative;
• the propagated recombinant yeast host cells express a heterologous nucleic acid molecule encoding a heterologous glucoamylase, wherein the heterologous nucleic acid molecule comprises a first polynucleotide encoding a heterologous signal sequence of SEQ ID NO:
• 5;
• and a second polynucleotide encoding the heterologous glucoamylase, wherein the heterologous glucoamylase is a secreted glucoamylase;
• and
• the first polynucleotide molecule is operatively associated with the second polynucleotide molecule;
• (iii) adding an exogenous glucoamylase to the biomass of the fermentor, wherein the added exogenous glucoamylase is displaced by at least 80% by weight when compared to a control fermentation;
• (iv) fermenting the biomass with the propagated recombinant yeast host cells in the presence of the exogenous glucoamylase to achieve an ethanol yield of at least 0.440% w/v of ethanol per w/w of biomass;
• and
• (v) recovering ethanol,
• wherein the recombinant yeast host cell is from the genus Saccharomyces.