Human microbiome

Tiny living things live on and inside you.

They live on your skin. They live in your mouth and your nose. They are even in your tummy.

These tiny things are not just one kind. They include things like bacteria. Some of them are very helpful. They live with you without causing harm.

Other tiny things can sometimes make you sick. Scientists study them to learn how they work. They look at the tiny parts of these living things. This helps us see how they live in our bodies.

Your body is home to many tiny living things. We call this collection the human microbiome.

These tiny life forms live in many places. They live on your skin and in your mouth. They are in your nose and your lungs. They even live in your gut, which is your digestive tract.

The microbiome includes many types of life. These are bacteria, fungi, viruses, and more. Some of these microbes are commensal. This means they live with you without causing harm. Others have a mutualistic relationship. This means they help you while you help them. However, some microbes can be harmful. They might make you sick.

Scientists study these tiny residents using DNA. DNA is a code found in all living things.

By looking at this code, they can see which microbes are present. The Human Microbiome Project is a big study of these life forms. In 2012, they shared many important results. They found that more than 10,000 different species live in humans. Every person has a slightly different mix of these tiny neighbors.

Your body is a busy home for many tiny living things. This massive collection is called the human microbiome.

These microbes live in many different spots. They reside on your skin and inside your mouth. They are also found in your nose and lungs. You can find them in your saliva and your gut.

This group includes bacteria, fungi, viruses, and protists. Some of these microbes are commensal, which means they live with you without causing harm. Others have a mutualistic relationship, where they help you and you help them.

Scientists use a special way to study these tiny neighbors. They look at DNA, which is the genetic code of life.

One way is called a targeted amplicon study. This method looks at specific marker genes to see what kinds of microbes are there. Another way is called a shotgun metagenomic study. This method looks at the whole group of genes to see what the microbes might be doing. Researchers must be careful to separate the tiny microbe DNA from your own human DNA. This helps them see the full picture of the microbial community.

Learning about these microbes has been a big job for many years. A major effort called the Human Microbiome Project, or HMP, was started to help. The HMP wanted to map the microbes that live in places like the skin and the nose. This project reached a huge milestone in 2012. On June 13, 2012, the director of the National Institutes of Health, Francis Collins, shared the results. He announced the findings through many scientific journals like Nature. This work helped create a reference database for scientists to use.

There are many amazing numbers inside the human microbiome. It is estimated that there are about 38 trillion bacterial cells in your body. This is very close to the 30 to 40 trillion human cells you have. The microbes also have a huge amount of genetic information. They have about 2 million bacterial genes. This is 100 times more than the 20,000 human genes in your body. The HMP studied 242 healthy volunteers from the United States. They collected over 5,000 samples from 15 to 18 different body sites.

Understanding the microbiome helps us understand our own health. Scientists want to know if there is a "core" group of microbes that every human shares. If they find this core, they might learn why some people get sick. The microbes in your gut can change from person to person. They can even change within the same person over time.

By studying how these tiny communities work, we might find new ways to treat diseases. We are learning how to keep these tiny ecosystems healthy and stable.

The human microbiome is the total collection of microorganisms living on or inside the human body. These microbes reside in many anatomical sites, such as the skin, the gastrointestinal tract, the lungs, and the oral mucosa. They are also found in the salivary glands, the uterus, the ovaries, and the biliary tract. This complex community includes several different types of life, such as bacteria, archaea, fungi, protists, and viruses. While micro-animals can live on the body, they are usually excluded from this scientific definition. Understanding this microbiome is vital because it represents a massive, living ecosystem that exists alongside our own cells.

Microorganisms interact with the human host in several distinct ways. Some are commensal, which means they live in our bodies without causing any harm. Others have a mutualistic relationship, where both the microbe and the human benefit from the interaction. However, some microbes can be harmful. Even if they are not pathogens, they can produce metabolites that cause issues. For example, the body converts trimethylamine into trimethylamine N-oxide through a process called FMO3-mediated oxidation. Scientists often refer to the microbes that are expected to be present and do not cause disease as the normal microbiota or normal flora.

Researchers study the microbiome using several advanced genetic techniques. One primary method involves studying deoxyribonucleic acid, or DNA. Scientists can use targeted amplicon studies, which focus on specific known marker genes to identify different types of microbes. A more recent method is the shotgun metagenomic study, which looks at the entire collection of genes to understand the functional potential of the community. Another way to study these organisms is through ribonucleic acid (RNA), proteins, or metabolites. A major challenge in these studies is separating the microbial DNA from the host's own human DNA.

To identify specific microbes, scientists often look for marker genes. For bacteria and archaea, the most common marker is the 16S rRNA gene. For fungi, researchers look at the Internal Transcribed Spacer, or ITS. These genes have highly variable regions that allow for detailed identification. They are also surrounded by conserved regions, which act as binding sites for primers during a process called PCR. This technique is fast and cost-effective, though it can sometimes lead to errors if the primers do not bind perfectly. To manage data, researchers often cluster sequences into Operational Taxonomic Units, or OTUs, based on a 97% similarity threshold.

One of the most significant scientific efforts in this field was the Human Microbiome Project, or HMP. The goal of the HMP was to sequence the genomes of the microbiota found in the skin, mouth, nose, digestive tract, and vagina. A major milestone occurred on June 13, 2012. On that day, Francis Collins, the director of the National Institutes of Health, announced the initial results. The findings were published in major scientific journals like Nature and the Public Library of Science. By mapping the microbial makeup of healthy humans, the HMP created a vital reference database for future research.

The scale of the human microbiome is truly immense when looking at the numbers. It is estimated that there are approximately 38 trillion bacterial cells in the human body. This is a similar order of magnitude to the 30 to 40 trillion human cells we possess. The genetic diversity is even more striking. While humans have approximately 20,000 genes, the bacteria in our bodies have an estimated 2 million genes. This means the microbial genome is about 100 times larger than our own. During the HMP, researchers analyzed over 5,000 samples from 242 healthy volunteers. They examined 15 to 18 different body sites to find more than 10,000 microbial species.

Scientists are currently working to understand if there is a "core" microbiome shared by most humans. If a core group of microbes exists, researchers might be able to link specific microbial compositions to different disease states. We know that the gut microbiota is highly variable between different people and even within the same person. However, there is evidence that the underlying microbial dynamics might be universal. By studying these ecological networks, scientists hope to develop new ways to treat diseases. Controlling these microbial communities could eventually help solve many harmful health problems.