Genetically modified lactate-consuming yeasts and fermentation processes using such genetically modified yeasts

A genetically modified yeast comprising:

• a heterologous gene encoding a polypeptide with monocarboxylic/monocarboxylate transporter activity, wherein the polypeptide with monocarboxylic/monocarboxylate transporter activity has an amino acid sequence with at least 90% sequence identity to at least one of SEQ ID NO:
• 24, SEQ ID NO:
• 26, SEQ ID NO:
• 28, SEQ ID NO:
• 76, or SEQ ID NO:
• 78;
• one or more heterologous genes encoding a polypeptide with D-lactate dehydrogenase (DLD) activity, wherein the polypeptide with DLD activity has an amino acid sequence with at least 90% sequence identity to at least one of SEQ ID NO:
• 40, SEQ ID NO:
• 42, SEQ ID NO:
• 64, SEQ ID NO:
• 66, SEQ ID NO:
• 68, SEQ ID NO:
• 70, SEQ ID NO:
• 72, or SEQ ID NO:
• 74;
• and
• one or more heterologous genes encoding a polypeptide with lactate dehydrogenase cytochrome b2 (CYB2) activity, wherein the polypeptide with CYB2 activity has an amino acid sequence with at least 90% sequence identity to at least one of SEQ ID NO:
• 15, SEQ ID NO:
• 17, SEQ ID NO:
• 54, SEQ ID NO:
• 56, SEQ ID NO:
• 58, SEQ ID NO:
• 60, or SEQ ID NO:
• 62;
• wherein the yeast is capable of consuming lactate and producing ethanol at a titer greater than 80 g/L when the yeast is present in a fermentation medium comprising lactate and hexose.