Researchers at Tufts University isolated microbes from real sourdough cultures to test whether simple pairwise interactions can predict community outcomes. The study, published in Ecology, measured how microbes grow alone and in pairs, then used those measurements to build a predictive model.
They tested the model with larger communities grown together in lab dishes, including mixtures of up to nine species. The model performed well: it reliably predicted which microbes would coexist and often matched their relative abundance. Only two of the nine species behaved differently from the model’s predictions.
To improve the fit, the team adjusted the model to reflect the sourdough starter life cycle, in which a portion is used for baking and the remainder is fed and regrown. Accounting for those repeated reductions and recoveries showed that slow-growing species may not reproduce enough to exclude others. The researchers note the same ideas could apply to other settings where populations crash and recover.
Difficult words
- isolate — to separate one thing for studyisolated
- microbe — a very small living organism, often single-celledmicrobes
- interaction — how two organisms affect each other's growthpairwise interactions
- model — a simple description used to make predictions
- coexist — to live or exist together in the same place
- relative abundance — how common each species is in the group
- life cycle — the repeating stages of growth and reproduction
- recovery — a return to a previous condition after a declinerecoveries
- exclude — to prevent something from becoming part of a group
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Discussion questions
- How could repeated reductions and regrowth in a sourdough starter affect which microbes survive?
- Do you think the same simple pairwise approach could predict outcomes in other communities, like soil or gut microbes? Why or why not?
- What reasons might stop a slow-growing species from surviving in a mixed microbial community?
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