Helmut König & Gottfried Unden 
Biology of Microorganisms on Grapes, in Must and in Wine 

The ancient beverage wine is the result of the fermentation of grape must. This n- urally and fairly stable product has been and is being used by many human societies as a common or enjoyable beverage, as an important means to improve the quality of drinking water in historical times, as therapeutical agent, and as a religious symbol. During the last centuries, wine has become an object of scientific interest. In this respect different periods may be observed. At first, simple observations were recorded, and subsequently, the chemical basis and the involvement of microorg- isms were elucidated. At a later stage, the scientific work led to the analysis of the many minor and trace compounds in wine, the detection and understanding of the biochemical reactions and processes, the diversity of microorganisms involved, and the range of their various activities. In recent years, the focus shifted to the genetic basis of the microorganisms and the molecular aspects of the cells, including metabolism, membrane transport, and regulation. These different stages of wine research were determined by the scientific methods that were known and available at the respective time. The recent “molecular” approach is based on the analysis of the genetic code and has led to significant results that were not even imaginable a few decades ago. This new wealth of information is being presented in the Biology of Microorganisms on Grapes, in Must, and in Wine.

Table of Content

Diversity of Microorganisms.- Lactic Acid Bacteria.- Acetic Acid Bacteria.- Yeasts.- Fungi of Grapes.- Phages of Yeast and Bacteria.- Primary and Energy Metabolism.- Sugar Metabolism by Saccharomyces and non-Saccharomyces Yeasts.- Metabolism of Sugars and Organic Acids by Lactic Acid Bacteria from Wine and Must.- Transport of Sugars and Sugar Alcohols by Lactic Acid Bacteria.- Secondary Metabolism.- Amino Acid Metabolisms and Production of Biogenic Amines and Ethyl Carbamate.- Usage and Formation of Sulphur Compounds.- Microbial Formation and Modification of Flavor and Off-Flavor Compounds in Wine.- Pyroglutamic Acid: A Novel Compound in Wines.- Polysaccharide Production by Grapes, Must, and Wine Microorganisms.- Exoenzymes of Wine Microorganisms.- Stimulaling and Inhibitary Growth Factors.- Physical and Chemical Stress Factors in Yeast.- Physical and Chemical Stress Factors in Lactic Acid Bacteria.- Influence of Phenolic Compounds and Tannins on Wine-Related Microorganisms.- Microbial Interactions.- Molecular Biology and Regulation.- Genomics of Oenococcus oeni and Other Lactic Acid Bacteria.- Genome of Saccharomyces cerevisiae and Related Yeasts.- The Genome of Acetic Acid Bacteria.- Systems Biology as a Platform for Wine Yeast Strain Development.- Plasmids from Wine-Related Lactic Acid Bacteria.- Rapid Detection and Identification with Molecular Methods.- Maintenance of Wine-Associated Microorganisms.- DNA Arrays.- Application of Yeast and Bacteria as Starter Cultures.