Abstract
The growing interest in new wine fermentation strategies, such as co-inoculating S. cerevisiae (Sc) and non-Saccharomyces (NS) species at the beginning of fermentation, requires a better understanding of howyeasts interact. Even though there are more and more studies on the interactions between Sc and NSspecies, few data are available on interactions between NS species. Moreover, it is still unknown whetherinteractions are more determined at the species or strain level. Thus, this study aims at determining therelative importance of species and strains in the interactions between 5 wine yeast species: Hanseniasporauvarum (Hu), Lachancea thermotolerans (Lt), Starmerella bacillaris (Sb), Torulaspora delbrueckii (Td) andSc. For this, we tested all possible pair cocultures between 15 strains (3 strains for each species) andcompared their growth to monocultures. We followed the growth in synthetic must for 24 hours with aplate reader. This way, we were able to identify four different types of growth compared to monocultures:cases where the coculture growth was close to the average growth of both monocultures, where thecoculture growth was closer to one of the monocultures, as well as cases where the coculture was eitherabove or under both monocultures. This finding would indicate that in most cases coculture behaviourdoes not result from the additive growth of monocultures. Besides, the type of interaction seemed to bemainly determined at the species level whereas the strain level was mainly modulating the interactionintensity. These results constitute a first step to a better understanding of the microbial dynamics occuringin wine fermentation. It would then be interesting to study how these interactions develop in morecomplex consortia involving higher order interactions.