Hi, welcome to the introductory lecture to Microbiota: Agents for Health and Disease.
My name is Brett Finlay,
and I'm from the University of British Columbia in Vancouver.
This is a fascinating series,
which looks at several aspects of the role of the microbiota,
both in their contribution to our health as well as disease.
This area has exploded recently in information,
and nearly every day,
we are finding something fascinating and new about
how these microbiota interface with our bodies.
This series consists of several talks by experts in the field
detailing many different issues and areas associated with the microbiota.
The purpose of this first lecture is to provide
a general overview to the series and introduce the topic.
For those of you that are specialists in microbiota already,
I urge you to go to the individual talks as this lecture is more of an overview.
However, in this lecture,
we will tackle several aspects of microbiota and just provide a tasting of
the various contributions these organisms play in both health and disease.
We will also discuss potential ways that we might be
able to manipulate these organisms for
our benefit as well as how they interface with the immune system and its development.
At the end of this lecture,
you will have a much better understanding in the general sense of how
the microbiota affect us and how they play
important roles in both our health and our disease.
To get this series started,
let's have a look at what exactly is the microbiome and what we mean by this term.
Generally speaking, the microbiome can be defined as
all the microbes in and on our bodies.
Now often, this seems to refer to bacteria,
but it also includes all the viruses and single-celled eukaryotes found in our body.
This is a fairly new term which has come into use,
and in the older literature,
this used to be called normal flora.
However, normal flora is not used anymore.
So, the microbiome consists of vast numbers of
microbes on various body sites that are usually exposed to the environment.
They're not usually found deep inside tissue or in the blood, et cetera.
So, really, it's the external surfaces in our body that can be
potentially exposed to microbes that actually get colonized.
This also includes the gastrointestinal tract as this
really is an access to the outside environment.
By far, the largest number of microbes are found in the intestine,
and it's calculated that one gram of feces
contains greater than 10 to the ninth bacteria,
which is more people than the entire world's population of humans.
The numbers are just mind blowing in that there is thought to
be at least 10 trillion human cells in a human body,
yet there's 100 trillion bacteria and
probably at least 100 times more than that in terms of viruses.
What we also know is that there's also
a hundred times more genetic material in microbes than in the human genome.
So, ironically, we're more microbe than human in this sense.
Its genetic material provides a vast reservoir of potential genetic pathways and
products these microbes can use as well as
allowing us to capitalize on their metabolic capacity.
We are still uncertain as to the exact number of microbes in and on us,
although we believe it's several thousand species,
although there is still discussion about what constitutes a microbial species.
And from a bacterial point of view,
only about a hundred of these could be potential bacterial pathogens.