The gut microbiome is so useful for human digestion and health that it is sometimes referred to as a special digestive organ. The vast collection of bacteria and other microorganisms in the gut help us break down food and produce nutrients and other metabolites that affect human health in countless ways. New research from the University of Chicago shows that some groups of these microbial helpers are also surprisingly resourceful, helping them generate their own energy, and have developed a large repertoire of genes that may also impact human health. It shows that you are prepared.
This paper was published on January 4, 2024. natural microbiologyidentified 22 metabolites that three distantly related families of gut bacteria use to replace oxygen for respiration in the anaerobic environment of the gut. These bacteria also have up to several hundred copies of genes for producing enzymes that process these alternative metabolites, far more than what has been measured in bacteria living outside the intestine. . These results suggest that anaerobic gut bacteria may have the ability to generate energy from hundreds of other compounds as well.
“These are some examples of unusual metabolisms that act on all these different metabolites that are produced by the gut microbiome,” said Dr. Neubauer, assistant professor of microbiology at the University of California, Chicago, and author of the study. said lead author Dr. Sam Wright. “This is interesting because one of the main ways the microbiome influences our health is by producing or modifying small molecules that can enter the bloodstream and act like drugs. Because it depends.”
At the biological level, we typically think of respiration as the process of breathing in oxygen. At the cellular level, respiration represents a biochemical process of energy production. Most cells use oxygen for respiration, but in anaerobic environments like the intestines, cells have evolved to use other molecules.
Cells have two major metabolic types to produce energy: fermentation and respiration. In fermentation, cells break down molecules to directly generate energy. Respiration involves two molecules: an electron donor and an electron acceptor. A typical example of this process uses glucose as the donor and oxygen as the acceptor. Cells break down glucose by shuttling the extracted electrons through a series of steps before ultimately transferring them to oxygen molecules. This prompts cells to produce ATP (adenosine triphosphate). ATP is the basic energy source for use and storage at the cellular level.
Most microorganisms that live in the intestine use fermentation, but some bacteria are known to perform respiratory metabolism, including those that use carbon dioxide and sulfate electron acceptors. For the new study, Wright and his colleagues analyzed his database of more than 1,500 genomes from the Human Gut Bacteria Database. They discovered a surprising distribution of genes that produce reductases, enzymes that use different respiratory electron acceptors. Most genomes encode only a few reductases, but a small subset encodes more than 30 different reductases. These bacteria were not closely related. They came from three different and distantly related families (Burkholderiaceae, Eggerthellaceae, and Marysipelotrichaceae), separated by hundreds of millions of years of evolutionary history.
These bacteria appear to be more resourceful than respiratory metabolic bacteria that live outside the host organism, using primarily inorganic compounds. The respiratory gut bacteria that Wright and colleagues identified specialize in a variety of organic metabolites, which makes sense given the constant supply of food.
“There’s a lot of organic matter in the gut that comes from the food we eat. Organic matter is chemically complex and requires more enzymes to adapt to its environment,” Wright says. “We think that this genetic diversity allows the gut bacteria to take advantage of a variety of incoming materials.”
Some of the metabolites they use have interesting effects on human gut health. For example, people with type 2 diabetes have higher levels of an amino acid byproduct called imidazole propionate in their blood. Another metabolite, resveratrol, affects several metabolic and immune system processes, and itaconic acid is produced by macrophages in response to infection.
Wright hopes further research like this will help us understand the function of different microbes in the gut, which can then be used to improve health.
“We hope that by understanding these different metabolisms and how they work, we will be able to develop strategies to intervene dietaryly or pharmacologically to modulate the flow of metabolites through different pathways. ” he said. “Therefore, we may be able to control which metabolites are produced to have a therapeutic effect in any setting, such as type 2 diabetes or after an infection.”
