2021•Unpublished venueRequires access
Yeasts
Pascal Ribéreau‐Gayon, Denis Dubourdieu, Bernard Donèche, Aline A. Lonvaud, Philippe Darriet, John Towey
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Abstract
This chapter discusses the morphology, reproduction, taxonomy, and ecology of grape and wine yeasts. Yeasts are the most simple of the eukaryotes. Like all plant cells, the yeast cell has two cell envelopes: the cell wall and the plasma membrane. The yeast cell wall is made up of two principal constituents: β-glucans and mannoproteins. The plasma membrane is a highly selective barrier controlling exchanges between the living cell and its external environment. Bounded by the plasma membrane and the nuclear membrane, the cytoplasm contains a basic cytoplasmic substance or cytosol. The organelles are isolated from the cytosol by membranes. The yeast nucleus is spherical. It has a diameter of 1-2βm and is barely visible using a phase-contrast optical microscope. Yeasts belonging to the imperfect fungi class can only reproduce by vegetative reproduction. Certain yeast strains, known as killer strains, secrete protein toxins into their environment that are capable of killing other, sensitive strains.