Snails as Taxis for a Large Yeast Biodiversity

Yeasts are unicellular fungi that harbour a large biodiversity of thousands of species, of which particularly ascomycetous yeasts are instrumental to human food and beverage production. There is already a large body of evidence showing that insects play an important role for yeast ecology, for their dispersal to new habitats and for breeding and overwintering opportunities. Here, we sought to investigate a potential role of the terrestrial snailsCepaea hortensisandC. nemoralis, which in Europe are often found in association with human settlements and gardens, in yeast ecology. Surprisingly, even in a relatively limited culture-dependent sampling size of over 150 isolates, we found a variety of yeast genera, including species frequently isolated from grape must such asHanseniaspora,Metschnikowia, MeyerozymaandPichiain snail excrements. We typed the isolates using standard ITS-PCR-sequencing, sequenced the genomes of three non-conventional yeastsH. uvarum, Meyerozyma guilliermondiiandP. kudriavzeviiand characterized the fermentation performance of these three strains in grape must highlighting their potential to contribute to novel beverage fermentations. Aggravatingly, however, we also retrieved several human fungal pathogen isolates from snail excrements belonging to theCandidaclade, namelyCa. glabrataandCa. lusitaniae.Overall, our results indicate that diverse yeasts can utilise snails as taxis for dispersal. This courier service may be largely non-selective and thus depend on the diet available to the snails.