Microbial communities in cheese identified

Harvard researchers have identified three general types of microbial communities that live on cheese.
A Bauer Fellow at the Harvard Faculty of Arts and Sciences' Center for Systems Biology, Rachel Dutton and her lab studied the bacteria and fungi that live on cheese, in an effort to better understand how microbial communities form.
After studying 137 varieties of cheese collected in 10 different countries, Dutton has been able to identify three general types of microbial communities that live on cheese.
This opens the door to using each as a "model" community for the study of whether and how various microbes and fungi compete or cooperate as they form communities, what molecules may be involved in the process and what mechanisms may be involved.

"We often use model organisms like E coli or C elegans because they can give us an understanding of the basic mechanisms and principles of how biology works," Dutton said.
"The goal of this work was to identify something like a model organism, but for microbial communities - something we can bring into the lab and easily replicate and manipulate.

"The challenge in studying these communities is that many of the environments where they are found, such as the human body or the soil, are hard to replicate because they're so complicated.
"Cheese seemed to offer a system in which we knew exactly what these communities were growing on, so we thought we should be able to replicate that environment in the lab," she said.

To understand what a model community might look like, Dutton and her lab first set out to identify dozens of naturally-occurring communities by collecting samples from the rinds of dozens of varieties of cheese around the world.
By sequencing the samples, Dutton identified the type of bacteria and fungi in each, and found that while there was wide variation among different samples, the samples could be separated into one of three main types of communities.
"What we ended up finding is there are microbes which occur in all the areas where cheese is made," she said.
"What was interesting is if you make the same type of cheese in France or in Vermont, they will have very similar communities.

"What seems to be driving the type of community you find is the environment that the cheese-maker creates on the surface of the cheese, so you can make two cheeses that are very similar in two different places, or you can make two very different cheeses in the same place," Dutton said.
Working in the lab, Dutton and colleagues were able to isolate each species of microbe and fungi found in the samples and conduct tests aimed at reproducing the communities found on different cheeses.
The study was also aimed at understanding how various species of bacteria and fungi interact, and identified several instances in which certain bacteria halted fungal growth, and vice versa.

The study is published in the journal Cell.