Author: Aline Lonvaud

Publisher: Frontiers Media SA

Published: 2019-08-16

Total Pages: 168

ISBN-13: 2889459594

Wine yeast and bacteria have been extensively characterized in terms of physiological and metabolic traits largely in pure culture analyses. Winemaking practices derived from this basic knowledge have undoubtedly improved wine quality. Phylogenetic studies and genome comparisons in extensive collections have revealed the processes of evolution and adaptation of the two main microbial species, Saccharomyces cerevisiae and Oenococcus oeni, present in wine. However, grapes and grape juice contain a variety of microorganisms and these principal agents of fermentation are in fact part of a complex microbial community that evolves dynamically in a special niche. Thanks to the new methods of analysis, the complexity of the microbiota can be measured in any sample of must or wine. In addition, there is greater appreciation of diversity within the main species present in wine. Intraspecific diversity has been evaluated in yeast and bacteria species and strains can be typed even in the mixture of selected or indigenous strains. Descriptions of microbial profiles in all the regions of the world suggest that the microbiota is a significant element of terroir or regional signature. It is no longer enough to simply describe what is present. It is important to consider evolution, physiology and metabolism taking into account microbial interactions within the community. Research in wine microbiology has also expanded our understanding of the participation and role of non-Saccharomyces organisms in winemaking, and refined knowledge on microbial spoilage. However, it is challenging to go from the simple description of these phenomena to their interpretation. The greatest difficulty lies in analyzing the functioning of the extraordinary complex system of yeast and bacteria present during different stages of the fermentation. Interactions in the very particular environment of fermenting grape induce alternations of relative populations’ dominances and declines with subsequent impacts on wine composition. Some mechanisms have been identified or suggested, but much remains to be done. The recent advent of inoculation with non-Saccharomyces in oenological practice, sometimes leading to inconstant results, reflects the profound gaps that exist in knowledge of the complexity of fermentation and wine microbial ecosystems. Understanding how the microbial community works is expected to provide a sound basis before using fermentation helpers and starters, taking into account the indigenous microbiota. It will also aid in monitoring and understanding native or uninoculated fermentations that rely on the complex interactions of grape, winery and fermentation biota for their aroma and flavor profile. The aim of this Research Topic was to bring together current knowledge on several key aspects of wine microorganism biology: i) Evolution / co-evolution of yeasts and bacteria in their process of domestication and adaptation to the oenological niche. ii) Mechanisms of interactions between species and strains, both on grapes and in grape must. iii) Metabolism and physiology of yeast and bacteria in interactions with each other and with the environment, considering to what extent expected objectives (typicity, lower alcohol, etc.,) can be reached by using selected strains. iv) Development of novel technologies or approaches for the assessment of changes in a dynamic microbial community and the linking of such changes to wine flavor and aroma properties. v) Diversity, ecology, physiology and metabolism of B. bruxellensis. Damage from this spoilage agent is not effectively prevented because we do not fully understand the biology of this species, particularly in interaction with other yeast and bacteria. Each chapter presents advances in these areas of study. Research in wine microbiology, particularly in the wine microbiome and its impacts on wine composition is enhancing our understanding of the complexities and dynamics of microbial food and beverage ecosystems.