Mixed Lactic Acid–Alcoholic Fermentation by Saccharomyes cerevisiae Expressing the Lactobacillus casei L(+)–LDH

The construction of a Saccharomyces cerevisiae strain expressing the gene encoding the L(+)–lactate dehydrogenase [L(+)-LDH)] from Lactobacillus casei is described, able to perform a mixed lactic acid–alcoholic fermenation.

Abstract

We describe the construction of a Saccharomyces cerevisiae strain expressing the gene encoding the L(+)-lactate dehydrogenase [L(+)-LDH)] from Lactobacillus casei. The recombinant strain is able to perform a mixed lactic acid-alcoholic fermentation. Yeast cells expressing the L(+)-LDH gene from the yeast alcohol dehydrogenase (ADH1) promoter on a multicopy plasmid simultaneously convert glucose to both ethanol and lactate, with up to 20% of the glucose transformed into L(+)-lactate. Such strains may be used in every field where both biological acidification and alcoholic fermentation are required.