Research identifies microbial
communities in cheese
Go
ahead and call Rachel Dutton's research cheesy if you must. As far as she's
concerned, it's anything but an insult.
A
Bauer Fellow at the Faculty of Arts and Sciences' Center for Systems Biology,
Dutton and her lab study cheese -- or more precisely -- 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, opening 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.
The study is described in a July
17 paper in Cell.
"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," she continued. "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."
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.
"We
did some travelling in Europe and worked directly with a number of
cheese-makers by having them send us samples or vising to collect samples, and
in some cases we were able to collect samples from places like Formaggio Kitchen
and other cheese shops," she said.
By
sequencing those samples, Dutton was able to identify 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."
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. "In many environments, it is
challenging to isolate all of the microbes, so we were surprised to find that
we could culture all of the species present on cheese rinds. This gives us a
great foundation for being able to study communities in the lab," says
Julie Button, a postdoctoral researcher in the Dutton lab.
"If
we know a particular cheese has certain species, we can mix them together and
try to recreate that community in the lab," Dutton said. "For
example, we might try to simply put those species together at the same time in
equal amounts to see if the community that forms is similar to that found in
the sample."
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.
"We
are now working with chemists to characterize what the molecules are that
different bacteria might use to kill a fungus," Dutton said. "It's
also possible that there may be anti-microbials that may arise from this that
are normally at play during the formation of a community."
While
wider applications for understanding how bacterial communities form may
eventually emerge, Dutton said there are still a number of fundamental
questions to answer in the short term.
"There
are so many wide open questions in thinking about how microbial communities
work, that future research could go in a number of different directions,"
she said. "Our goal is to understand some of these fundamental questions,
such as: Are there certain principles that are operating as a community forms,
and can we control those factors in the lab?
"Cheese
is fascinating to me in its own right -- it's somewhat surprising that, for a
food that we've been eating for thousands of years, we don't have a complete
understanding of the microorganisms that are present in this food."
But
now that Dutton has that understanding, does she still eat cheese?
"I
do," she said with a laugh. "But I'm very picky, because I like very
good cheese now."
Story Source:
The
above story is based on materials provided by Harvard
University. Note:
Materials may be edited for content and length.
Journal Reference:
1.
Benjamin E.
Wolfe, Julie E. Button, Marcela Santarelli, Rachel J. Dutton. Cheese
Rind Communities Provide Tractable Systems for In Situ and In Vitro
Studies of Microbial Diversity. Cell, 2014; 158 (2): 422 DOI:10.1016/j.cell.2014.05.041
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Harvard University. "Choosing cheese: Research identifies
microbial communities in cheese." Science Daily, 17 July 2014.
<www.sciencedaily.com/releases/2014/07/140717180538.htm>.