We do not have the same microbes—a new study published in PLOS Computational Biology explains why.
Why don’t you and I have the same microbes? All humans have thousands of species of bacteria all over and inside their bodies, a relationship that is essential to our life. A great proportion of these microorganisms are found in our alimentary canal where they help us digest food (so, no, they are not harmful!), and another important collection of microbiota lives in our skin, protecting us from disease-causing bacteria, among other reasons. On the other hand, the microbial species living intimately with (and within) us differ from person to person. Apparently, this difference is due to the variation in resources used by these microbes.
Competition for resources, for instance, will create the unique individual collections of microbiota: one person will have more of one specific species than another person, and so on. Behind these findings is a team of researchers from École Normale Supérieure, Paris, led by Charles Fisher; the group aimed at understanding the effects of availability of resources on the human microbiota.
Fisher and his team designed a mathematical model to draw the link between the abundance of microbial species and the availability of the resources they use—this is based on the ecological viewpoint that dictates how two species depending on the same resources will increase and decrease in number in synchrony with each other. Also, the results were coupled with the Human Microbiome Project—documenting microbial species in the human body—whose data was re-analysed using new statistical methods.
The findings show that availability of resources varying across different body sites can impact on the relative abundance of microbial species present in the specific regions. Another important result is that, species sharing resources appeared to be closely-related—this implies that taxonomic relationships might influence the correlation between the relative abundance of two species.
The next step is now to focus on this aspect of human microbiota and diseases. This study entailed the microbes of healthy humans, but it could pave the way to investigating resource availability in diseases pertaining to microbiota, like Crohn’s disease, says Fisher. He also thinks that their study can help scientists develop treatment for a condition called dysbiosis, which is a microbial imbalance in or on the body.