Gut microbes have a vital bearing on our health by producing vitamins, priming our immune system and developing resistance to pathogens.
For example, studies have shown that the insulin resistance of type-2 diabetics is linked to intestinal bug composition and can be beneficially altered by replacing it with that of healthy donors.
The genes of our gut microbes, also known as the microbiome, act as a personalised organ that can be modified by diet, lifestyle and antibiotics. This organ is fed partly by us and partly by our diets.
Willem M.de Vos, professor in microbiology at the Helsinki University (Finland), and colleagues have classified the human microbiome into three enterotypes: clusters of microbiomes with similar compositions and nutrient-processing preferences, according to a Helsinki statement.
These enterotypes are characterised by bacteria with different capacities to degrade carbohydrate and mucin (gel-forming protein which produces mucus). Our gut microbes get carbohydrates partly from our diet, whereas the mucin is produced by our own body.
“We have evolved with the microbes in our gut, our microbes inside, and have discovered that they talk to us and we feed them with, among other things, the mucins we produce,” said de Vos.
“We now are trying to unravel their functions and understand exactly what these microbes and their products mean to human health.”
The size of one microbial metagenome (one host’s microbiome) is 150 times larger than the human genome and encodes 100 times more genes than our own genome.
This extensive gene catalogue could enable us to study potential associations between microbial genes and human phenotypes and even environmental factors like diet, throughout the length of our lifetime.