Patent ID: 7534597

Claim:
A process for integrating an exogenous lactate dehydrogenase gene into a yeast cell, wherein prior to the integration the cell has a targeted gene at a locus in its genome, comprising the steps of (a) transforming the cell with a recombinant nucleic acid having a lactate dehydrogenase (LDH) gene, flanking sequences upstream and downstream of the LDH gene, and at least one selection marker gene, said flanking sequences being homologous to flanking sequences upstream and downstream of the targeted gene, such that the LDH gene is inserted into the genome of the cell adjacent to the locus of the targeted gene in a single crossover event, (b) selecting for first transformants containing the LDH gene and the selection marker gene, (c) nonselectively growing said first transformants and (d) selecting among such first transformants for second transformants that contain the LDH gene but have deleted the selection marker gene and the targeted gene.