The yeasts are a phylogenetically diverse group of fungi characterized by unicellular growth. Yeasts have been used for bread making and brewing beverages for millennia, and have become increasingly important in biotechnology for production of fuel alcohol, organic acids, enzymes, and various pharmacologically important chemicals. Other species are serious human, animal, and plant pathogens. Since publication of the 3rd edition of this book in 1984, numerous new species and genera have been described, many because of the application of new molecular biological methods. Molecular comparisons have now provided a phylogenetic distinction between the yeasts and other fungi, some of which have a unicellular growth phase.This book is the most definitive treatment of taxonomy and systematics of yeasts available and has been prepared by an international team of experts and is directed at taxonomists, ecologists, mycologists, microbiologists, clinicians, molecular geneticists, and biotechnologists.