More recently, the interactions in multi-starter fermentation of T. debrueckii and S. cerevisiae in a double-compartment bioreactor system were investigated 22• and 23. Cell-to-cell contact mechanisms and the release of soluble lethal molecules appear to be the actions involved in T. delbrueckii early death. Regarding to the first mechanism, the quorum-sensing-like phenomena in yeast
have been only recently investigated to explain the morphological transition from filamentous to mycelial or yeast form even if this phenomenon could be also involved in some yeast interactions. In this context, the identification of quorum-sensing active molecules and their influence on gene expression of yeast co-culture could be an http://www.selleckchem.com/hydroxysteroid-dehydrogenase-hsd.html attractive approach to investigate on wine yeast interactions. On the other hand, the production of proteinaceous metabolites can have a significant role on the presence and dominance of yeast species during mixed fermentations. Recently, a strain Trametinib price of S. cerevisiae known as CCMI 885 was studied for its ability to produce a toxic compound that kills some non-Saccharomyces strains in mixed fermentation, such as Kluyveromyces marxianus, K. thermotolerans, Hanseniaspora guillermondii and Dekkera bruxellensis, thus showing strictly species-dependent antimicrobial effects. This antimicrobial effect is produced by S. cerevisiae and was identified
as small cationic peptides that correspond to fragments of the protein glyceraldehyde-phosphate dehydrogenase, and the involvement of these peptides in microbial interactions in mixed fermentation was demonstrated [24•]. Other antimicrobial Amino acid compounds such as killer toxins are involved in wine
yeast interactions. The killer phenomenon has been widely described in winemaking and among wine-yeast species. While S. cerevisiae killer yeast show a narrow spectrum of action, as only against strains belonging to the same species , non-Saccharomyces killer yeast show wide inter-generic killer actions. Among these non-Saccharomyces killer yeast, several proteinaceous compounds have been found to be active in grape juice and/or wine. Some of these have been identified and well characterised, and their main significant characteristics are reported in Table 1. In this regard, the control of undesired proliferation of H. uvarum and Brettanomyces/Dekkera spoilage yeast might be carried out using controlled mixed fermentation with non-Saccharomyces killer yeast. In this way, the killer strains have potential as biocontrol agents to counteract undesirable wine-spoilage yeast, although further investigations in this field are needed. Indeed, the last findings 24•, 26, 27 and 28 suggest that the bioactive compounds in wine such as proteinaceous compounds, fatty acids and cyclic higher alcohols, may play a fundamental role in yeast interactions ( Table 2).