Please wait while the transcript is being prepared...
0:00
I'm Dr. Primrose Freestone.
I'm an Associate Professor
in Clinical Microbiology
and I'm going to be explaining
to you why microbial metabolism
is important to life
on planet Earth.
0:15
By the end of this lecture,
you should understand
the following:
the different types
and functions
of metabolic pathways
in microorganisms;
how the applications of
these pathways are important
in yeast and
bacterial metabolism
in industrial processes;
how microbial
metabolism actually
drives Earth element cycling;
and how the products of
microbial metabolism are
sustainable and contribute
to human well-being.
0:45
To remind you then,
metabolism is the set
of chemical reactions that
occur in living organisms.
Metabolic processes,
anabolism and catabolism,
allow microorganisms to grow,
maintain their structures,
and respond to
their environments.
Importantly, some
of the byproducts
of microorganisms
such as amino acids,
nucleotides, and indeed
their so-called
waste products are
rather important for
biotechnology processes.
What is a waste product to
a bacteria or fungal yeast cell
might not necessarily
be to a human.
Indeed, the ethanol
and lactic acid,
that are waste products
of sugar metabolism by lactic
acid bacteria and yeast
are the foundations of huge
biotechnology industries.
1:39
In terms of types of metabolism,
chemoheterotrophs obtain
carbon and energy from
pre-made organic
compounds such as
carbohydrates,
lipids, and proteins.
Indeed, for chemoheterotrophs,
most of the cell's
energy is generated
from the oxidation of
carbohydrates, usually sugars.
Glucose is utilized by
most chemoheterotrophs
and there are two major
types of glucose metabolism.
There's what occurs in
the presence of oxygen
called respiration,
in which glucose is
fully metabolized to
carbon dioxide and water.
So glucose plus oxygen
gives CO_2, water,
and electrons which
then, through
electron transport schemes,
can generate up to 36 ATPs.
We also have, in the absence
of oxygen, fermentation
where glucose is only
partially metabolized
to several different products.
They are usually principally
ethanol and lactate.
Why is this important?
Well, it allows these
microorganisms to grow
and inhabit niches
where there are
relatively few
other competitors.
In the presence of oxygen,
there are thousands
and thousands of
different species
of microorganisms.
But where there's
little or no oxygen,
there are many, many
fewer microbes present.
Those microbes undergoing
a fermentative form
of energy generation
from sugars,
generally speaking,
have less competition.
But of course at the same time,
because they're getting
less ATP from the glucose,
they need to have
much higher levels of
enzymes involved in the
processing of glucose,
which we'll look at shortly.
