The total number of microbes that colonize the surfaces of our adult bodies is thought to be ten times greater than the total number of our human cells.
Our microbial partners provide us with certain features that we have not had to evolve on our own. In this sense, we should consider ourselves to be a supraorganism whose genetic landscape includes both our own genome as well as the genomes of our resident microbes, and whose physiologic features are a synthesis of human and microbial metabolic traits.
The largest collection of microbes resides in our gut, which harbors trillions of bacteria, representing hundreds of species, most falling into two groups—the Bacteroidetes and the Firmicutes.
We have sequenced the genomes of two human gut-dwelling Bacteroidetes, and compared their genomes to the genomes of other bacteria that live both inside and outside of our bodies.
Our results illustrate that adaptation to the gut habitat is a dynamic process that includes acquisition of genes from other microorganisms.
These findings emphasize the importance of including the evolution of “our” microbial genomes when considering the evolution of humans.
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Amb el temps i una canya en Lammark es farà el seu raconet. En la discussió final...
"Because the environment surrounding each human being varies, this gene flow may promote the generation of host-specific microbiomes. Acquisition of new types of carbohydrate binding proteins, transporters, and degradation enzymes through both LGT and gene amplification should influence the types of substrates that can be exploited for energy harvest. It may also affect our predisposition to conditions such as obesity in which the efficiency of caloric harvest may be influenced by the relationship between an individual's microbial glycoside hydrolase repertoire and the glycan content of his/her diet"
I no cal esperar milions d'anys ....