Not About a Virus

C. Roullier-Gall, V. David, D. Hemmler, P. Schmitt-Kopplin, & H. Alexandre: “Exploring Yeast Interactions through Metabolic Profiling”, Scientific Reports (2020).

How about we discuss some research that isn’t about the current pandemic? One of my college housemates always referred to yeast as “yeast-buddies” when we were brewing or in reference to my work as a winemaker. Let’s look at some recent yeast research in preparation for the impending crush.
I came across this paper that was just published by Scientific Reports. Winemakers have to be practical microbiologists as they herd yeast, and bacteria, through their respective fermentations. Few winemakers, however, seem to stray beyond yeast ranching.
Metabolomics is a type of systems biology that focuses on the intermediate substrates of metabolism. A textbook definition might read as, “Metabolomics is the study of the unique chemical composition, or fingerprints, of particular cellular processes.” The important concept, at least to me and gentle readers should know that I am not an expert, is that these metabolic processes are studied in living systems and not in isolation.
What Roullier-Gal et alia found was that, “Distinct metabolites appeared in wines from sequential fermentation compared to single fermentation.” This is significant because it suggests that the use compatible yeast species during fermentation is in producing a different post-fermentation make-up than might be produced if the same yeast species were used separately.

Abstract

As a complex microbial ecosystem, wine is a particularly interesting model for studying interactions between microorganisms as fermentation can be done by microbial consortia, a unique strain or mixed culture. The effect of a specific yeast strain on its environments is unique and characterized by its metabolites and their concentration. With its great resolution and excellent mass accuracy, ultrahigh resolution mass spectrometry (uHRMS) is the perfect tool to analyze the yeast metabolome at the end of alcoholic fermentation. this work reports the change in wine chemical composition from pure and mixed culture fermentation with Lachancea thermotolerans, Starmerella bacillaris, Metschnikowia pulcherrima and S. cerevisiae. We could clearly differentiate wines according to the yeast strain used in single cultures and markers, which reflect important differences between the yeast species, were extracted and annotated. Moreover, uHRMS revealed underlining intra species metabolomics differences, showing differences at the strain level between the two Starmerella bacillaris. non volatile metabolomics analysis of single and sequential fermentations confirmed that mixed fermentations lead to a different composition. Distinct metabolites appeared in wines from sequential fermentation compared to single fermentation. This suggests that interactions between yeasts are not neutral.

Link:
 https://www.nature.com/articles/s41598-020-63182-6

DOI:
https://doi.org/10.1038/s41598-020-63182-6