In this week’s National Geographic, biologist Michael D. Moo describes a recent study in which he used a microscope to investigate how microbial communities within the human gut are responding to changes in diet.
“Our work suggests that the human microbiome may be changing over time, and this can have a profound impact on our health,” he says.
Moom is a professor at Harvard University’s Department of Biological Sciences and a founding director of the Microbiomes Project at Harvard Medical School.
He is the author of a paper, “Bioluminecent Microorganisms in the Human Gut.”
Moom and his team of scientists have previously shown that microbes in the human colon are more responsive to diet than to the environment.
But this study is the first to show how the microbiome, and the changes it’s making, affect health.
In the new study, Moom’s team found that the bacterial communities of the colon were less responsive to changes from food and water than to changes associated with changes in microbes in a person’s gut.
Moot’s team also found that changes in the microbes of the gut affect health differently for people of different races, genders and age groups.
For example, people who are white, who typically live longer, had fewer bacteria that responded to diet changes than those of other races.
But people who were darker-skinned and more likely to have certain chronic illnesses — such as Crohn’s disease and ulcerative colitis — had fewer resistant bacteria than people who had less of these problems.
“We don’t know how or why the microbiome is changing over the course of our lives,” Moom says.
“But this research has provided an exciting window into the microbiome as a whole.”
For the new research, Moot and his colleagues used a special type of microscope, which uses light to focus light into individual bacterial cells, rather than scanning a large sample.
The microscope’s focus is so that a tiny droplet of light can enter the cells to study a tiny patch of bacterial DNA.
That small patch of DNA is called a single-stranded DNA, which is made up of just two bases.
The researchers then examined the single-spaced DNA in the guts of mice, and compared the genomes of mice that had been genetically modified to have more of the single, single-sulfate version of the gene that codes for the enzyme that breaks down the single sulfate version.
The mice had the single-, single- and single-S variants in their guts, respectively.
“These findings provide an important new tool for understanding how the microbes in our gut interact with each other and to our environment,” says Moo.
“This is the kind of work that we’re interested in because it provides a glimpse into how we might be influencing the microbiome in different ways.”
Moo and his collaborators used this new technique to study the gut microbiome of the mice.
“The more we study the microbiome of our bodies, the more we learn about how that affects our health, and what the impacts of that might be,” he adds.
“What is it that we eat, what are we exposed to, what can we change to help?”
Moo’s team was able to pinpoint which microbes had altered over the years by sequencing their genomes.
But their findings were only possible because the researchers collected stool samples from mice.
Because stool is the most common source of bacteria found in the colon, the researchers knew that they would need to do more research to see how the different microbes in their gut changed.
Moooo and his group started by using stool samples to determine what the bacteria in the mice’s guts were changing.
They also collected stool and urine samples to analyze how they responded to changing diets.
To do this, they used a technology called polymerase chain reaction (PCR) that can read the chemical makeup of the DNA in bacteria and other living organisms.
The scientists then combined all of the data to create an overall picture of the bacteria’s response to changes.
By comparing these results with previous studies, they were able to determine which microbes in mice’s gut were changing the most, and which were changing less.
“In our study, we found that a significant proportion of the changes in gut bacteria were linked to the consumption of carbohydrates,” Moo says.
That means that a large number of bacteria in mice ate more carbohydrate than other bacteria.
Moos and his researchers were able also to show that the gut microbes in these mice were also changing more rapidly, so they had to be doing something to keep them in balance.
They then studied the microbial populations in mice who were fed a diet high in fat.
“When we were eating more fat, the gut bacteria in our mice were doing very well,” Moot says.
This suggests that they were doing something by altering their gut microbial communities.
“Some bacteria were changing into resistance to some of the compounds in fat, and some of these resistance genes are being turned on,” he explains.
“As a result, these microbes