Stanford University scientists have successfully created the first human microbiome in a laboratory by combining 119 types of bacteria found in the body that they believe could lead to treatments for life-threatening gut infections.
Gut microbiomes are made up of hundreds of species of bacteria that live in the human digestive system and play important roles in human health by supporting the immune system and controlling digestion.
The synthetic microbiome was transplanted into mice, where it multiplied, protecting the animal from E. coli and triggering the development of a healthy immune system.
Researchers say they can now look at each microbe individually to uncover its role, allowing doctors to mix cocktails of microbes to create tailored treatments.
The team mixed the 119 species of bacteria and then cultured them where they stabilized. The colony was transplanted into mice, where it was found to protect the animal from infection and help it build a healthy immune system
There are about 30 trillion cells in the human body, but the human microbiome is made up of about 39 trillion microbial cells, including bacteria, viruses, and fungi.
The gut microbiome controls the storage of fat and helps activate the genes in human cells involved in the absorption of nutrients, the breakdown of toxins, and the formation of blood vessels.
These microorganisms also replenish the lining of our gut and skin, repairing damaged cells and replacing dead cells with new ones.
And they fend off invading microbes, which the Stanford team wants to analyze in their study.
Researchers say they can now look at each microbe individually to uncover its role, allowing doctors to mix cocktails of microbes to develop tailored treatments (stock photo)
“Many important microbiome studies have been performed using stool transplants, which introduce the entire, natural microbiome from one organism into another,” the team said in a statement.
“While scientists routinely turn off a gene or remove a protein from a specific cell or even an entire mouse, there is no such toolbox to remove or modify one species among the hundreds in a given stool sample.”
Deciding to build their colony from the most common bacteria, the researchers turned to the Human Microbiome Project (HMP), a National Institutes of Health initiative, to sequence the complete microbial genomes of over 300 adults.
Michael Fischbach, institute scientist at Sarafan ChEM-H and corresponding author of the study, said in a statement, ‘We have been searching for Noah’s Ark of bacterial species in the human gut and trying to find those that have almost always been present in each individual.’
Fischbach and his team selected 166 strains of bacteria found in the majority of people, but were only able to obtain 104, reports the New York Times.
The 104 species were bred in individual stocks and then mixed into a single culture to form a community of 119 strains, which the team calls Human Community One, or hCom1.
The strains could coexist in laboratory culture, but the team needed the same in a living being’s gut.
They introduced hCom1 into mice designed to be devoid of bacteria, and hCom1 was remarkably stable, with 98 percent of the constituent species colonizing the gut of these germ-free mice and the relative abundance of each species remaining constant over two months.
Then the team gave the mice a new community of 119 strains called hCom2, which made mice even more resistant to fecal challenges than the first.
The second iteration group was exposed to E. coli, but their intestines fought off the infection.
Previous studies have shown that a healthy natural microbiome confers protection, but Fischbach and colleagues could go a step further by iteratively eliminating or modifying specific strains to determine which specifically confer protection.
They found several key bacteria and plan to conduct further studies to narrow down the most critical species.
Fischbach believes that hCom2 or future versions of it will enable similar reductionist studies that uncover the bacterial agents involved in other areas, such as immunotherapy responses.
“We built this consortium for the wider research community. We want to put this in as many hands as possible in order to make an impact on the field,” said Fischbach.
