The magnitude and variability of phage populations during wine making remain so far unexplored. The few available data on phages of oenological origin have been obtained in the 1980-90s and are restricted to phages infecting lactic acid bacteria, in relation with the capacity of some species to conduct malo-lactic fermentation (MLF). The process, which reduces acidity and increases microbial stability, is largely driven by Oenococcus oeni, which is the best adapted species to the harsh conditions prevailing in wine. Pioneering studies mostly targeted oenophages associated with red wines under MLF, and offered alternative explanations to the delayed or stuck MLF that are often encountered by winemakers. However, the genetic and biological diversity of oenophages remained largely unexplored and most viruses were not subsequently characterized beyond their description by electron microscopy, and lytic spectra.

Our first objective was to get more information on phage diversity in order to further explore the ecological roles of oenophages and their impacts on spontaneous MLF. The second objective was to document about the interactions between phages and commercial strains. Indeed, in modern oenology, predictable MLF starters are available under ready-to-use concentrated cultures. The presence of lytic phages able to infect starters as well as the possibility that prophages have impact on the properties of their host are also of great interest for strain design.

A large survey of oenophages has been conducted in samples collected from different types of wine, appellations, estates around Bordeaux, and stages along the wine making process and resulted in the isolation of temperate and virulent phages. We show that phages in O. oeni are incredibly varied in their properties, from host range, genetic content to persistence capacities. Diversity and comparative genomics of oenophages as well as their relationships with phages infecting other LAB genera are discussed.