Abstract
Fermentation by microorganisms is a key step in the production of traditional food products such as bread, cheese, beer and wine. In these fermentative ecosystems, microorganisms interact in various ways, namely competition, predation, commensalism and mutualism. Traditional wine fermentation is a complex microbial process performed by Saccharomyces and non-Saccharomyces (NS) yeast species. To better understand the different interactions occurring within wine fermentation, isolated yeast cultures were compared with mixed co-cultures of one reference strain of S. cerevisiae with one strain of four NS yeast species (Metschnikowia pulcherrima, M. fructicola, Hanseniaspora opuntiae and H. uvarum). In each case, we studied population dynamics, resource consumed and metabolites produced from central carbon metabolism. This phenotyping of competition kinetics allowed us to confirm the main mechanisms of interaction between strains of four NS species. S. cerevisiae competed with H. uvarum and H. opuntiae for resources although both Hanseniaspora species were characterized by a strong mortality either in mono or mixed fermentations. M. pulcherrima and M. fructicola displayed a negative interaction with the S. cerevisiae strain tested, with a decrease in viability in co-culture. Overall, this work highlights the importance of measuring specific cell populations in mixed cultures and their metabolite kinetics to understand yeast-yeast interactions. These results are a first step towards ecological engineering and the rational design of optimal multi-species starter consortia using modeling tools. In particular the originality of this paper is for the first times to highlight the joint-effect of different species population dynamics on glycerol production and also to discuss on the putative role of lipid uptake on the limitation of some non-conventional species growth although interaction processes.
Highlights
In natural or anthropized environments, microbial species are part of an ecosystem and interact positively or negatively, forming a complex network
We compared in winemaking conditions, the performance of single cell cultures of five different strains from five yeast species (Saccharomyces cerevisiae, Metschnikowia pulcherrima, Metschnikowia fructicola, Hanseniaspora opuntiae and Hanseniaspora uvarum) and mixed co-cultures combining each of the four NS species with one GFP-labelled S. cerevisiae strain representing 10% of the initial inoculate
By comparing the output of single strain and mixed strain cultures, we evaluated the intensity of yeast-yeast interactions and/or their consequences on ecosystem service production
Summary
In natural or anthropized environments, microbial species are part of an ecosystem and interact positively or negatively, forming a complex network. Efforts are being made to design optimal consortia of various species and strains whose interactions will be exploited to maximize given criteria such as fermentation quality, aromatic complexity or other organoleptic characteristics. Wine fermentation is both an economically and societally important food ecosystem, where the addition of fermentation ‘starters’ composed of selected yeasts at the beginning of the fermentation process is common. Around 80% of oenological fermentations worldwide are conducted with starters [1,2] Most often, these “starters” are only composed of a single Saccharomyces cerevisiae (S. c.) strain selected for its ability to complete fermentation. They most often combine one strain of S. cerevisiae allowing to complete fermentation and another species, often from a different genus, contributing to a greater variety of flavors [3,4,6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
