AP Biology class blog for discussing current research in Biology

Tag: GutMicrobiome

Discovering and Using Your Personal, Biological, Tiny Army

Bacteria is an important part of our biology, so important that we are essentially 99% bacteria. A lot of this bacteria is part of the human gut microbiome. This topic has been picking up interest in the field of biology, and have shown linkage to many diseases such as inflammatory bowel disease and obesity. Not only do the bacteria in our gut play a role in preventing these diseases, but their symbiotic relationship helps us maintain metabolic functions.

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This is a depiction of the numerous types of bacteria in our microbiome.

Until recently we were unable to study these bacteria due to our inability to cultivate them in a lab; however, due to new advancements in sequencing technology we can now see how big of  role they play in our biology and our functions. These bacteria are “estimated to harbor 50- to 100-fold more genes, compared to the hose. These extra genes have added various type of enzymatic proteins which were non-encoded by the host, and play a critical role in facilitating host metabolism.” For example, gut microbiata is very important in fermenting unabsorbed starches. These bacteria also aid in the production of ATP. A certain type of bacteria generates about 70% of ATP for the colon with a substance called butyrate as the fuel.

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This image shows the interaction between the gut and the immune system. The immune system targets bacteria, but somehow not our gut bacteria. 

Another large role of the gut microbiome is its interactions with out immune system and nervous system. The bacteria in our gut suppress the inflammatory response in order to not be targeted by the immune system. This allows for a symbiotic relationship between us and the bacteria inside of us. This allows the gut bacteria to help regulate the inflammatory response without being stopped by the very thing it’s regulating. Without these bacteria our inflammatory responses would be completely out of the ordinary.

These findings with gut bacteria are fairly new and there is much more to come regarding their use in the field of medicine. Something to think about that I found fun was how little of us is really human. Ninety nine percent of you is bacteria, which essentially means that we are pretty much just giant colonies of bacteria. Kind of gross/amazing when you think about it.

Microbes Role in Evolution

In the human body, there are trillions of bacteria that come together to make a collective group called microbiomes. These cells are an essential part of the human body and regulate our risks to get obesity, asthma, and allergies. Considering microbials help our bodies function, researchers then are wondering if microbials have played a critical role in our evolution. In an article by Carrie Arnold a writer at Scientific American, she illustrates microbiome’s effect on evolution through two studies on insects.

Microbiome’s Effect on Mate Selection

Eugene Rosenberg of Tel Aviv University conducted an experiment in 2019 which found that raising fruit flies on different diets changed their mate selection. During this experiment, the fruit flies would choose to mate with flies with the same diet as them. The flies would revert back to there original mating patterns after they were given antibiotics. The results showed that the changes in the gut microbes from the diet caused the flies to change their choice of mate.

Microbiome’s Effect on Longevity and Ability to Reproduce

In 2011 Geneticist Seth Borderstein at Vanderbilt University conducted an experiment with two types of termites – Zootermopsis angusticollis and Reticulitermes flavipes – to test an organism’s life span and their ability to make offspring. The study found that after the study the antibiotic fed termites had less of a variety of gut bacteria and fewer offspring. The lead researcher Borderstein then concluded that there were important microbes reduced by the antibiotics. Because microbes help with digestion and the absorption of nutrients this reduction left the termites malnourished thus producing fewer eggs.


These two studies help to illustrate that researchers can no longer see a separation between an organism’s genes and their microbiomes. They both work together in a single hologenome. One of the researchers, Rosenberg, says that by looking at the history of botany and zoology we can see how billions of microorganisms are connected to most animals and plants. Scientists have to look at hologenome in order to understand an organism. Microbiomes are also important in human evolution too. This is shown through human adaptations of digestion, smell, and the immune system. Borderstein says that these changes over time are very likely to be a product of microbiomes in the body. Bordenstein ultimately argues “the microbiota are as important as genes.”

Baboons: A closer insight to understanding the Human Gut Microbiome

In a recent Northwestern University article, a new study was found that despite human’s close genetic relationship to apes, the human gut microbiome is more closely related to that of “Old World” monkeys, such as baboons than to that of apes like chimpanzees. Another article posted by Medical News Today, provided more insight on why we should specifically take a deeper look into Old world monkeys, such as baboons, to tell us more about the human microbiome. Maria Cohut, the author of the article, claims that since these baboons are closer related to humans and share 99% of their DNA with humans, they will provide clues about the human gut microbiome. 

The results also suggested that human ecology has had a stronger impact in shaping the human gut microbiome than genetic relationships. They also suggest the human gut microbiome may have unique characteristics, like an increased flexibility. In a quote by Katherine Amato,  lead author of the study and assistant professor of anthropology in the Weinberg College of Arts and Sciences at Northwestern, she explains that it is essential to understand what factors shaped the human gut microbiome over evolutionary time because it can help us understand how gut microbes may have influenced adaptation and evolution in our ancestors and how they interact with our biology and health today. She also adds that host ecology is what drives microbiome function and composition, since chimpanzees have different habitats, diets, and physiology than humans. In order to understand the human gut microbiome we must look at primates that are similar to humans since ecology is the, she also adds. Although chimpanzees are often assumed to be the best module for humans in many aspects, it is evident that this close relationship doesn’t apply when comes to analyzing the gut microbiome. 

Going forward, Amato and her team are planning on exploring which qualities of the human gut microbial functions are shared with Old World monkeys and what impact they have on human biology and physiology. The results of this study demonstrate that the human gut microbiome diverges from closely genetically related apes and converges with “cercopithecines both taxonomically and functionally.” These findings provides deep insight on the evolution of microbiomes. More importantly, the results highlight the importance of human ecology and digestive physiology in shaping the gut microbiome. Intimately exploring the relationship between baboons, or other close human related mammals, could reveal more in-depth information about the human gut microbiome and how different factors of our environment affect it. 

Exercise causes changes in our gut microbes, but how is unclear

Sarah Campbell was just beginning her assistant professorship in exercise and science at Rutgers University when she became curious about whether exercise could influence microbes in the gut. As an athlete and also having studied cholesterol metabolism and exercise and diet during her PhD and postdoc, she decided that she wanted to pursue the study of exercise and its affect on gut microbes.

Sarah Campell combined forces with microbiologists and toxicologists from Rutgers and a pathologist from Oklahoma City to create an experiment to analyze fecal samples of male mice who are fed a normal or high-fat diet for 12 weeks. Some of the mice in each group were allowed to exercise while others weren’t. The results revealed that physical activity created a unique microbiome in the guts of mice, independent of the diets of the mice. The mice that exercised hosted Faecalibacterium, Clostridium, and Aloobaculum, unlike the sedentary mice. The high-fat diet also led to inflammation in the guts of the mice who didn’t exercise, and this was not seen in the mice that ate a fatty diet and exercised.

The following picture is of gut microbiota (microorganisms that live in the digestive tracts of humans)

The results of this experiment reinforced findings that came out a few years before that showed how exercise prevented weight gain and altered the gut microbes in mice that became obese while eating a high-fat diet. The results of the experiment also aligned nicely with a study that found that lean, sedentary people who exercised for six weeks developed increased levels of Clostridiales, Lachnospira, Roseburia, and Faecalobacterium in their guts. In addition, the study showed how these microbes returned back to baseline levels once the individuals stopped exercising. Obese individuals who began exercising also had changes to their gut microbes; however, these changes were different than those seen in the lean individuals.

Even though the reasons for the difference in changes between the obese and lean individuals aren’t fully understood, the results clearly show how exercise can change the gut microbiota of humans, regardless of diet or body composition.

Mothers, Babies, and the Gut Microbiome

In the past, doctors knew there were certain women were at a higher risk for having premature babies, such as having high blood pressure, diabetes, or multiples, but doctors have only recently discovered the significance of a woman’s microbiome at the beginning of the chain reaction in a woman’s body ending in birth.

Stanford researchers have created an “Immune Clock” using multiple factors, such as the mother’s “gut, vaginal and oral microbiomes, blood levels of proteins and metabolism-related molecules, plus fetal genetic material released into the women’s blood”. They have found that this algorithm creates extremely accurate results and currently has thousands of data points.

In a separate study, scientists discovered that women with more diverse inflammation microbes in their microbiome were more likely to miscarry. Although this research is interesting, broad conclusions are hard to draw because each woman has a different microbiome, based on not only their genetic makeup, but also their diet, environmental factors, and emotional stress.

Interestingly, a mother’s microbiome is not the only important factor for a premature baby. In a University of Rochester study on premature babies’ stool, they discovered the importance of a baby’s gut microbiome. Premature babies with more “good” bacteria in their diapers tend to fare better than those with less.

The image above shows a baby whose diaper will soon likely contain gut bacteria!

Today, many doctors in the NICU push premature babies to consume more calories, although this method alone often does not result in growth. Certain gut bacteria essential to growth thrives on different groups of food, and since there is a high importance in having distinct stages of a baby’s gut microbiome development, adjusting the baby’s nutrient consumption may help it to grow and thrive.

The often-overlooked property, the gut microbiome, has proved itself as an essential contributor to both mothers and babies to thrive. Would you ever submit your data to the Immune Clock to find out your risk of having a premature baby?

Gut Microbiome is Responsible for PTSD?

Recently, there have been many studies linking gut microbiome to PTSD. But how exactly are they connected?

Humans have an infinite number of organisms creating a unique composition of bacteria in the gut. It has been suspected before that any number of combinations of these gut microbiome can affect our health in different ways. One way is that they can cause neuropsychiatric disorders like PTSD or even just weaken mental toughness. Either way, the topic of gut microbiomes is definitely worth researching.

A recent study conducted by 22 scientists at Stellenbosch University in South Africa showed that compared to healthy, unaffected people, those with PTSD had noticeably lower levels of three gut bacteria: Actinobacteria, Lentisphaerae, and Verrucomicrobia. However, it was also noted from that study that the loss of these three gut bacteria may have occurred in earlier stages of life rather than the later stages when people generally develop PTSD.

According to a study conducted by researches of Oregon State University, when someone suffers from stress, their gut microbiomes become disordered and start to act oddly. Therefore, the lower levels of the three gut microbiomes could indicate that the levels of those microbiomes are throwing off the balance that is needed to maintain a stress and anxiety free mind which can prevent PTSD.

There is one catch about this result: that correlation does not confirm anything. Scientists conducting studies could only identify a correlation with gut microbiome and PTSD, but could not determine a cause.

Many are hopeful that these results will lead to discovery of future treatments because the microbiome can easily be changed with prebiotics, probiotics, synbiotics, or just dietary changes.

Although we do not know if these three gut microbiomes cause PTSD or come with PTSD, we do know that we are now one step closer to finding a cure or at least a better treatment for PTSD.

For more information click here or here!

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