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0:00
Hello. My name is
Gabriel Trueba,
and I will be
speaking to you about
the evolutionary perspectives
of the human microbiota.
0:11
The outline of the
presentation will be:
the microbiota description,
the current view
about microbiota,
bacterial genetics and
evolution, microbiota stability,
selective forces in microbiota,
selective forces in animal
hosts, and conclusions.
0:29
So what is the human microbiota?
First of all, I would
like to differentiate
the two terms microbiota
and microbiome.
Microbiota is just the group
of microorganisms that we
have in the intestine,
whereas microbiome is
the group of organisms,
the genes, the functions,
the metabolism, etc.
So it's a much
more complex term.
During the presentation,
I will be talking about
these two terms almost
interchangeably.
The largest contributor
to human microbiota,
the intestinal
microbiota, is bacteria.
We have around 1000
bacterial species
and a different
number of strains
belonging to a given species.
So there's a very great
diversity in the intestine.
1:22
I'm going to talk about
the prevailing view
of the human microbiome,
and that's what you find
in the current literature
about the human
intestinal microbiome.
So most of the
papers that you see
emphasize on bacterial
species and not the strains.
I'm going to show
you that's a problem
with the current view
of the microbiota.
This approach ignores
horizontal gene transfer.
Sometimes you can read that
some bacteria are good,
some bacteria are bad.
For instance, Prevotella copri
is thought to be
a good bacterium.
E. coli is thought to be
maybe not so good bacteria.
So in the next slide
you'll see that
this view is not correct.
It should be more
complex the way that
we approach the human
intestinal microbiome.
The other view that I
think is not correct
is that the microbiota
is mutualistic,
which means that it
benefits both bacteria and
human hosts more or
less at the same level.
This view sometimes goes
as far as to say that the
microbiota is a human organ.
Also, many people mentioned that
the microbiota is
something stable.
So if you have a microbiota,
that microbiota is
going to stay with you
for the rest of your life
as long as you keep
eating the same food
or have the same way of life.
I would like to talk
a little bit about
