Whether different microbial species co-exist depends on who they are rather than what you feed them

What is it about?

We know that several microbial species can live together in the simplest environments because they feed on each other's waste chemicals, but we don't know which species we expect to end up in stable communities. This paper is the first to take the same community of four species and test it in many different simple environments to see which species goes extinct when. To our surprise, the species coexisted in 57 out of the 58 environments we tested. We found that this was because of how many chemicals they generate in their waste and how they each prefer to grow on different chemicals.

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Photo by Waldemar Brandt on Unsplash

Photo by Waldemar Brandt on Unsplash

Why is it important?

First, it helps to answer one of the central questions in microbial ecology: why so many microbial species can live together, even if we expect them to compete for scarce resources and drive each other extinct. Second, it suggests that we can begin to predict which species are likely to live together based on their characteristics. Third, many efforts in biotechnology aim to combine multiple microbial species rather than using pure cultures, yet achieving stable coexistence remains challenging. Our work provides principles for designing microbial communities that remain stable across a wide range of nutrient conditions. In other words, we are moving from simply knowing that many species can coexist because they feed one another, to understanding which species are likely to coexist, and why.

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