This demonstrates that if we learn about the natural ecology of bacterial competition, we might be able to manipulate microbiomes rationally. We wrote about this more broadly in a recent review.
doi.org/10.1016/j.ch...

When we then supplemented that private nutrient for the invading strain, boom, the resident strain was displaced by the invading strain!

Then, we took a community of gut microbes that included a resident antimicrobial E. coli clinical isolate and identified a nutrient that was not consumed by any species in the community. We then added an invading strain of E. coli that could use that private nutrient, and gave it a bacterial weapon.

Bacterial weapons only start to take effect once a strain has invaded. If the invading strain carries a weapon and can grow to a sufficient density based on its metabolism and available nutrients, it can now displace a resident strain!

We confirmed this first with theory and then with experiments.

It turns out that invasion of a strain into a community is not facilitated by bacterial weapons, but rather by differences in nutrient utilization. This fit really well with our recent work on nutrient blocking in colonization resistance: www.science.org/doi/10.1126/...

We began by thinking about how microbes naturally compete in communities. It happens in two main ways: bacteria use metabolic capacity to access nutrients better than competitors via resource competition, or they invest in bacterial weapons to kill competitors called interference competition.

Replaced by my favourite, the mountain goat, this time 😁

Very fun collaborative piece with @vit-pi.bsky.social and Kevin Foster