Lessons from the first man-made human microbiome

Did you know that we have about as many microbes living in and on our bodies as we have human cells?! This means that we share our bodies with about 30 trillion microorganisms. Even though this number is more or less the same for all humans, it’s important to note, that just like we are all unique when it comes to our genetic make-up, there is no ONE human microbiome. We all differ in the composition of microbes in our microbiome and the way they work together and relate to one another.

Microbiome research is still in its beginning stages, as scientists only started sampling microbial species living in our bodies less than twenty years ago (1).To this day, we don’t know how many species make up a healthy microbiome. What we do know is, that microbial diversity is an indicator for health. This begs the question: How many microbes are needed to form a stable microbiome that can survive and withstand invaders?

To understand the workings of the microbiome and to be able to treat diseases better, more and more studies are being done and this field of research is growing day by day. For example, changing the microbiome’s composition in order to treat gut-related diseases has already been done for years – with fecal transplants. Yes, you heard that right: There are several studies (2) stating improvements in patients’ health outcomes after altering their gut microbiome by transplanting fecal matter (3) from a healthy person into their gut.

In this article we are taking a look at a recent breakthrough in microbiome research, that might change the way we work with the microbiome in the future: Scientists at Stanford University were able to make the first synthetic human microbiome (4), using species that are naturally found in the human body.

How they did this? They determined over a hundred microbial species that are common in most people. The scientists then created a mixture, put it into mice that were reared to have no microbiome and observed how the microbes behaved. After several tests, Dr. Cheng, Dr. Fischbach and their colleagues discovered 119 strains of microbes that were needed to form a stable microbiome that could sustain itself and formed its own ecosystem in these germ-free mice.

The scientists found what they were looking for when they exposed mice with this synthetic microbiome to human stool samples. They observed that these mice were not only able to withstand pathogens but also make digestive fluids and develop a healthy immune system – unlike germ-free mice. (4)

These promising findings pave the way for further research and enable scientists to study individual microbes and how they relate to other strains. Because, once a stable microbiome is established, one can add or take away certain microbes and see how this affects the whole system.

It’s safe to say that this first discovery of 119 species making up a stable microbiome in mice, is only the beginning of further research in this area. As we know, the microbiome plays a part in countless processes in the body. Understanding it better, will provide us with many ways of going about improving our wellbeing – be it skin-(5) or gut-related or in regards to overall health.

So, in the name of our wellbeing: Let’s encourage diversity and cooperation.