50 YEARS AGO
Rachel Dutton’s research is cheesy, by
design. The microbiologist at the University
of California, San Diego uses cheese rinds
to study how microbes form communities.
Dutton, who has a long-standing interest in how bacteria and other microbes
interact, got the inspiration for her studies
several years ago while visiting the Marine
Biological Laboratory in Woods Hole,
Mass. In the salt marshes there, multiple
species of bacteria, archaea and other
microbes were growing in thick, many-layered mats. They would have been
perfect for studying microbes in groups.
Except for one thing: Many organisms that
thrive in those mats won’t grow in captivity. Dutton needed a microbe community
that she could pick apart, manipulate and
reconstruct in the lab.
The solution came with a round of cheese
from France. Sliced open, its rind reminded
Dutton of the microbial mats on the coastal
salt marshes. “I took a piece of cheese into
the lab and put it under the microscope,”
she says. “Everything I was looking for in a
microbial community was present.”
Dutton and colleagues did genetic anal-
yses of 137 cheeses from 10 countries and
identified 24 genera of bacteria and fungi
that are common in cheeses and will grow
in the lab, the team reported in 2014 in the
By sampling a Vermont cheese as it
aged over 63 days, the group also discovered that rind communities don’t form
instantly. At the beginning, community
members included Proteobacteria and
Leuconostoc bacteria, plus candida yeast
commonly found in raw milk. Within a
week, Staphylococcus had overwhelmed
the Proteobacteria. As the cheese ripened,
Brevibacterium and Brachybacterium
plus Penicillium and Scopulariopsis fungi
UPDATE: An estimated 100 to
200 people get leptospirosis
annually in the United States.
The disease, which can cause
fever, headache and vomiting,
is most common in tropical
and rural regions worldwide.
Summertime swimming is
also haunted by another
single-celled terror that
thrives in warm freshwater:
the so-called “brain-eating”
amoeba, Naegleria fowleri. The
amoeba caused 35 reported
infections in the United
States from 2005 to 2014. If
N. fowleri enters a person’s
nose, it can travel to the brain,
where swelling triggered by
the immune system kills most
victims (SN: 8/22/15, p. 14).
Excerpt from the
May 14, 1966
issue of Science News
Bacteria and fungi, like the Penicillium camemberti
shown here (top), work together to give cheeses
their texture and flavor. Microbiologist Rachel
Dutton got the inspiration to study cheese when
she realized that cheese rinds (left, a rind from
a washed rind cheese) resemble microbial mats
(right) from salt marshes and other locations.
THE SCIENCE LIFE
As warm weather
approaches, the old swimming hole will again beckon
boys and girls in farm areas.
But disease germs lurk in
waters exposed to cattle
and other animals…. One
“swimming hole disease”
called leptospirosis is caused
by water-borne Leptospira
pomona…. Warm summer
temperatures are ideal for
organisms in water, and
heavy rains may transport
the organisms downstream.
became prominent inhabitants of the rind.
That pattern held whenever those organisms congregated in a cheese in the lab.
Cheesemakers from Vermont taught
Dutton how to ferment cheese curds and
create her own lab version of a dry-aged
cheddar. Although cheeses can have complex combinations of microbes — stinky
cheeses have the most diverse mixes —
Dutton’s lab crafts a more simplified rind
using three types of fungi and four bacteria. The researchers grow the microbes in
pairwise combinations to learn how they
Studying cheeses and other fermented
foods could teach scientists how microbial
communities evolved in different places
and lead to the creation of new, tastier and
safer foods, Dutton and Benjamin Wolfe of
Tufts University wrote last year in Cell.
There’s one drawback to the cheesy
research: The lab has a ripe odor, Dutton
says. “We look like a normal microbiology
lab, but we don’t smell like one.”
— Tina Hesman Saey
Fungi and bacteria shape the distinctive
characters of a wide range of cheeses.