To apply these biotechnological
procedures, Galunisertib mouse better knowledge of the physiological and metabolic interactions between S. cerevisiae and non-Saccharomyces wine yeast is needed. In this context, controlled multi-starter fermentations might be an interesting way to investigate yeast interactions during wine fermentation. In this review, we will discuss the recent developments regarding yeast interactions in multi-starter wine fermentation, while focusing on the influence on the yeast growth and the analytical and aroma profile of the wine. Due to the non-sterile environment during wine fermentation, different yeast species and/or strains can be involved in several interactions through the production of toxic compounds, or as a result of competition for nutrients. In terms of inhibitory interactions that are mediated by metabolites with toxic effects, the most evident example is the production of GSI-IX cell line ethanol by S. cerevisiae. Indeed, the selective pressure exerted by high levels of alcohols has been defined as the main factor responsible for the
dominance of S. cerevisiae towards other non-Saccharomyces yeast . Together with ethanol, other factors can have strong selective pressure in mixed wine fermentation. In particular, the production of medium-chain fatty acids and high amounts of acetic acid can negatively affect the growth of a co-fermenting yeast species. Cell-to-cell contact appears to be also involved in the interactions between S. cerevisiae and other non-Saccharomyces species, such as Torulaspora delbrueckii, Hanseniaspora uvarum and Kluyveromyces thermotolerans (now reclassified as Lachanchea thermotolerans) . Another mechanism that regulates the presence and dominance of yeast species
during wine fermentation is the involvement of oxygen. Amylase Reduced oxygen availability under grape juice fermentation might have an important role as a selective factor in mixed cultures. Indeed, low tolerance to low available oxygen exhibited by K. thermotolerans and T. delbrueckii could in part explain their relative competitiveness, and consequently their rapid death in the presence of S. cerevisiae . For a broader understanding of the complex phenomenon of microbial interactions a multifactorial approach is required. We belief that this kind of approach may be a useful tool to investigate on the influence of these different factors affecting the presence and the dominance of yeast strain in mixed fermentation.