The interaction of Saccharomyces paradoxus with its natural competitors on oak bark

The natural history of the model yeast Saccharomyces cerevisiae is poorly understood and confounded by domestication. In nature, S. cerevisiae and its undomesticated relative S. paradoxus are usually found on the bark of oak trees, a habitat very different from wine or other human fermentations. It is unclear whether the oak trees are really the primary habitat for wild yeast, or whether this apparent association is due to biased sampling. We use culturing and high-throughput environmental sequencing to show that S. paradoxus is a very rare member of the oak bark microbial community. We find that S. paradoxus can grow well on sterile medium made from oak bark, but that its growth is strongly suppressed when the other members of the community are present. We purified a set of twelve common fungal and bacterial species from the oak bark community and tested how each affected the growth of S. paradoxus in direct competition on oak bark medium at summer and winter temperatures, identifying ...