Genetic Engineering of Microorganisms in Winemaking

Abstract

This chapter discusses various aspects of transgenic wine yeasts and wine-associated lactic acid bacteria. The wine fermentation and post-fermentation steps have become more sophisticated and automated. S. cerevisiae are diploid/aneuploid, occasionally polyploidy, mainly homothallic, exhibiting chromosomal length polymorphism, possessing multiple translocations, while the lab-bred strains are haploid or diploid. In order to design new wine yeasts for commercial applications, several classical approaches were successfully applied. Some of the problems faced in sexual hybridisation can be overcome by rare-mating or alternate hybridisation. Industrial wine yeasts are usually diploid or polyploid because of the presence of two copies or more; they lack auxotrophic mutations, restricting the selection process of mutants. Selectable transformation markers are essential for strain improvement by genetic methods. Winemaking is not merely alcoholic fermentation; modern wineries rely on carefully selected starter cultures for obtaining consistent and reliable products. The concept of winemaking is going through a period of change, experimentation and adaptation.