[Applause]
thank you I’m a microbiologist and I
study ecological interactions among
microorganisms within their communities
and living the environment today I’m
going to talk to you about methane its
importance on the earth and some amazing
relationships that bacteria transforming
methane have perhaps you know methane as
the most important component of natural
gas because methane is odorless when
it’s used in residential applications
we had a chemical to allow you to detect
its smell so that does not build up
potentially causing an explosion methane
has a simple chemical formula ch4 in
fact it’s the smallest but it’s the most
abundant hydrocarbon firstly we use
methane as a fuel but 28 trillion cubic
feet of methane are consumed each year
in the US with about 1/3 going to
industrial use 1/3 going to electricity
production in a smaller fraction being
used for residential and commercial
heating natural gas as a fuel is only
surpassed in the u.s. by petroleum but
as a fuel natural gas composes about 26%
of our energy use unfortunately methane
is also a greenhouse gas with about 10
times the potency of carbon dioxide what
that means is that every molecule of
methane in the atmosphere reflects back
about 10 times as much heat as a
molecule of carbon dioxide in the same
location in that respect methane is the
second most important greenhouse gas
next to carbon dioxide methane can be
formed through high-temperature
biogeochemical processes or geochemical
processes and deep rock or it can be
formed by bacteria that live in
sediments and soils it gets into the
atmosphere in a variety of ways
about a third of it is released from
natural gas and petroleum deposits but
of the remaining sources of methane
about 50% of them are human related and
by far the vast majority of that methane
is produced by bacteria aside from the
petroleum related sources the primary
source of methane or a major source of
methane is the enteric fermentation this
is methane that’s produced in digestion
during digestion by cows sheep goats and
yaks the acts are important this cloth
these animals all have a large digestive
organ where they break down grasses and
other plant materials to a variety of
products including methane the methane
is released by irritation that is
belching the total methane released from
this source is directly related to the
number of grazing animals out there
perhaps there’s a solution one of them
is for you to eat less meat another it’s
fairly simple we could trap the methane
before we can trap the methane before
it’s released to the atmosphere and this
has actually been implemented so some of
you are asking to yourselves hopefully
whether whether humans produce methane
whether we have methane producing
bacteria and our GI tract and that’s
where I’m pointing down here and the
answer is that some of us do but even in
those people by far the most important
source the most important gas that’s
produced and released by these processes
is not is not methane but it’s hydrogen
and carbon dioxide okay
there there are a couple of other human
human related sources of methane that
are very important one of them is this
management of animal waste management of
waste from cows pigs and chickens when
these theses are contained the naturally
occurring bacteria break down partially
degraded feeds producing methane and
carbon dioxide and landfills are also
another source of methane all of the
trash that you produce ends up in a big
hole in the ground that we cover with
soil and called the lamp call a landfill
think about what’s in your trash food
paper building materials these can also
these can all be converted to methane
and carbon dioxide by soil bacteria
finally this other category is extremely
important this includes places locations
where plant growth and subsequent burial
or storage occur I’m talking about
wetlands peat bogs and tundra soils
this is not the most important source of
methane at the moment but it’s receiving
a huge amount of attention by scientists
and this is because there’s a lot of
carbon a lot of plant derived carbon
stored in these locations as global
warming occurs soils will warm
dramatically increasing rates of methane
formation and thawing permafrost soils
making carbon available for conversion
to methane okay I think it’s time to
talk about who makes methane and by that
I mean the bacteria involved I actually
have a number of favorite bacteria but
these methane producing bacteria at the
top of my list bacteria right you can
line up about 10,000 of these
microorganisms across the face of a dime
these methane producing bacteria are
special and their story goes back a long
time the earth is about 4.5 billion
years old and during the first 2.5
billion years of the Earth’s history the
earth was a rough place to live there
was no oxygen in the atmosphere and so
respiration as we know it using oxygen
did not occur when I discussed
respiration I’m referring to a cellular
process of breaking down to food in the
presence of an oxidant and producing
energy which is used for cell growth or
other processes like standing up here
and giving a talk for example the
atmosphere on the early earth contained
primarily carbon dioxide and nitrogen
and so when bacteria were looking for a
chemical to respire carbon dioxide was
the most abundant compound so as life
and respiration evolved on the early
earth respiration of carbon dioxide to
methane became a dominant process this
methane producing bacteria developed a
very complex mechanism very complex
biochemical
mechanism for producing methane but even
now these bacteria use a very limited
range of foods they’re illustrated here
these compounds these chemicals that
they use as foods were abundant on the
early earth but are much less abundant
now as bacteria and plants and animals
have evolved over the billions of years
of Earth’s history to produce more and
more complex chemicals these bacteria
have not increased their repertoire of
nutrients they’ve taken the strategy of
teaming up with an unrelated organism
the process is called sin trophy which
literally means feeding together the
strategy involves one bacterium breaking
down a complex chemical and feeding its
products to a methane producing
bacterium that use those to grow so how
does this work
these bacteria must seek out a partner
and they do this by recognizing
chemicals that are located on the
outside of the cells of the other
organism of the other bacterium and
swimming towards it this bacterium must
be close together to growth centrally
there are two strategies in one case the
close proximity is required for these
bacteria to most efficiently exchange
nutrients alternatively these bacteria
can just exchange electrons they do this
using what we call electrically
conductive nanowires
these are filaments made up of proteins
and metals and these cells are connected
by an electrically conductive network
that allows these cells to carry out the
complete conversion of complex organic
chemicals to carbon dioxide and methane
now this bacteria evolved in an
environment that was devoid of oxygen
and as a result these bacteria cannot
tolerate oxygen so methane production
only occurs in environments in which
oxygen is depleted this thing this
includes most of the locations that I’ve
talked about already room and wetlands
landfills tundra soils etc there’s
another part of this story at least from
an ecological perspective you may be
wondering whether all the methane that’s
produced actually makes it to the
atmosphere after all that methane
typically must pass through soils must
pass upwards typically through soils and
sediments that could potentially benefit
from the large amount of energy that’s
available and there is a large amount of
energy provided that there’s a suitable
oxidant available like oxygen in ocean
sediments and bottom waters that oxidant
is sulfate or nitrate but in soils and
wetlands oxygen is used here’s an
example of an amazing system where
methane is partially or fully oxidized
before it makes it to the atmosphere a
number of years ago I worked on a peat
bog here’s an example of a peat bog in
Latvia the one I worked on was called
Thoreau’s bog and the guy with the
mustache is one of my colleagues this is
in northern Massachusetts these peat
bogs are abundant they’re located in
northern areas northern part of the US
Canada Northern Europe they were formed
as glaciers moved south carving divots
in the ancient rock that’s present in
these locations as these holes filled up
with water this spagna Moss began to
grow and Spagna modifies its environment
decreasing the pH releasing acids
ensuring its survival in the system
because of the low ph of the water and
the relative lack of oxygen previous
years growth of the sphagnum Moss decays
quite slowly and as a result you end up
with literally thousands of years of
moss thousands of years of dead plant
material growing underneath the live
plant as this material of the case
methane is released methane is formed
and then released and actually gets
trapped up in the decaying plant
material serving to allow this entire
plant and dead plant emits and it
actually floats like a raft so you can
walk out on it and these people are
actually walking out on this layer of
this layer of sphagnum and other
materials that’s perhaps a meter or two
thick and there’s water underneath so as
the methane is produced underneath it
actually moves upwards and some of it
ends up being oxidized to carbon dioxide
some of it makes it up to the atmosphere
this same process occurs in wetlands all
around the world for example in the öyou
duck pond the upper part of the o-u duck
pond is an awesome wetland there’s
methane produced and then this methane
passes through plants that have the
potential to oxidize it perhaps an
interesting part of this story is that
the bacteria that convert the methane to
carbon dioxide are not located on the
outside of the plant as we would have
expected they’re actually located within
the plant cells these bacteria are
present in a symbiotic relationship with
this plant in which the plant provides
shelter for these bacteria and the
bacteria either provide nutrients or
energy to the plant
okay I’ve spoken about a number of
complex relationships
bacteria transforming methane are
involved in now that we were beginning
to understand the mechanisms for these
relationships we can begin to develop
technologies that take advantage of this
information perhaps the most obvious
potential application is in the energy
industry methane can be oxidized and in
nature this process involves the removal
of electrons a number of scientists have
developed what we call microbial
batteries or microbial fuel cells that
take advantage of microorganisms and
their mechanisms and their reactions to
produce energy from waste waters to
produce electricity from waste waters we
can think about similar process
developing a microbial battery to use
methane to generate electricity
this power could be used on site or it
could be pumped into the electrical grid
conversely electricity has the potential
to be used in a microbial system to
produce methane directly this could be
used when surplus power is available and
we will have surplus power as we expand
our solar power production I recently
obtained some funding from the National
Science Foundation to study novel
methane oxidizing bacteria and some
colleagues on this project are
interested in value-added products from
methane perhaps the most obvious example
the most obvious chemical is methanol
methanol is a liquid fuel that can be
much more easily transported and stored
than methane it also has a number of
industrial uses my colleagues are
interested in biodegradable polymers
these are chemicals that are produced by
bacteria that can be used to substitute
for plastics and do not last forever
when they’re released into the
environment these bacteria also have the
potential to produce proteins for either
medical or biotech
logical uses finally as we improve our
understanding of methane transformation
we can get a better idea a clear picture
of the factors that limit methane
release to the atmosphere environmental
scientists are always looking for better
ways to predict the flux of greenhouse
gases to the atmosphere so they can
determine what sort of changes in human
activities are needed to slow down
climate change thank you for your
attention
[Applause]
thank you I’m a microbiologist and I
study ecological interactions among
microorganisms within their communities
and living the environment today I’m
going to talk to you about methane its
importance on the earth and some amazing
relationships that bacteria transforming
methane have perhaps you know methane as
the most important component of natural
gas because methane is odorless when
it’s used in residential applications
we had a chemical to allow you to detect
its smell so that does not build up
potentially causing an explosion methane
has a simple chemical formula ch4 in
fact it’s the smallest but it’s the most
abundant hydrocarbon firstly we use
methane as a fuel but 28 trillion cubic
feet of methane are consumed each year
in the US with about 1/3 going to
industrial use 1/3 going to electricity
production in a smaller fraction being
used for residential and commercial
heating natural gas as a fuel is only
surpassed in the u.s. by petroleum but
as a fuel natural gas composes about 26%
of our energy use unfortunately methane
is also a greenhouse gas with about 10
times the potency of carbon dioxide what
that means is that every molecule of
methane in the atmosphere reflects back
about 10 times as much heat as a
molecule of carbon dioxide in the same
location in that respect methane is the
second most important greenhouse gas
next to carbon dioxide methane can be
formed through high-temperature
biogeochemical processes or geochemical
processes and deep rock or it can be
formed by bacteria that live in
sediments and soils it gets into the
atmosphere in a variety of ways
about a third of it is released from
natural gas and petroleum deposits but
of the remaining sources of methane
about 50% of them are human related and
by far the vast majority of that methane
is produced by bacteria aside from the
petroleum related sources the primary
source of methane or a major source of
methane is the enteric fermentation this
is methane that’s produced in digestion
during digestion by cows sheep goats and
yaks the acts are important this cloth
these animals all have a large digestive
organ where they break down grasses and
other plant materials to a variety of
products including methane the methane
is released by irritation that is
belching the total methane released from
this source is directly related to the
number of grazing animals out there
perhaps there’s a solution one of them
is for you to eat less meat another it’s
fairly simple we could trap the methane
before we can trap the methane before
it’s released to the atmosphere and this
has actually been implemented so some of
you are asking to yourselves hopefully
whether whether humans produce methane
whether we have methane producing
bacteria and our GI tract and that’s
where I’m pointing down here and the
answer is that some of us do but even in
those people by far the most important
source the most important gas that’s
produced and released by these processes
is not is not methane but it’s hydrogen
and carbon dioxide okay
there there are a couple of other human
human related sources of methane that
are very important one of them is this
management of animal waste management of
waste from cows pigs and chickens when
these theses are contained the naturally
occurring bacteria break down partially
degraded feeds producing methane and
carbon dioxide and landfills are also
another source of methane all of the
trash that you produce ends up in a big
hole in the ground that we cover with
soil and called the lamp call a landfill
think about what’s in your trash food
paper building materials these can also
these can all be converted to methane
and carbon dioxide by soil bacteria
finally this other category is extremely
important this includes places locations
where plant growth and subsequent burial
or storage occur I’m talking about
wetlands peat bogs and tundra soils
this is not the most important source of
methane at the moment but it’s receiving
a huge amount of attention by scientists
and this is because there’s a lot of
carbon a lot of plant derived carbon
stored in these locations as global
warming occurs soils will warm
dramatically increasing rates of methane
formation and thawing permafrost soils
making carbon available for conversion
to methane okay I think it’s time to
talk about who makes methane and by that
I mean the bacteria involved I actually
have a number of favorite bacteria but
these methane producing bacteria at the
top of my list bacteria right you can
line up about 10,000 of these
microorganisms across the face of a dime
these methane producing bacteria are
special and their story goes back a long
time the earth is about 4.5 billion
years old and during the first 2.5
billion years of the Earth’s history the
earth was a rough place to live there
was no oxygen in the atmosphere and so
respiration as we know it using oxygen
did not occur when I discussed
respiration I’m referring to a cellular
process of breaking down to food in the
presence of an oxidant and producing
energy which is used for cell growth or
other processes like standing up here
and giving a talk for example the
atmosphere on the early earth contained
primarily carbon dioxide and nitrogen
and so when bacteria were looking for a
chemical to respire carbon dioxide was
the most abundant compound so as life
and respiration evolved on the early
earth respiration of carbon dioxide to
methane became a dominant process this
methane producing bacteria developed a
very complex mechanism very complex
biochemical
mechanism for producing methane but even
now these bacteria use a very limited
range of foods they’re illustrated here
these compounds these chemicals that
they use as foods were abundant on the
early earth but are much less abundant
now as bacteria and plants and animals
have evolved over the billions of years
of Earth’s history to produce more and
more complex chemicals these bacteria
have not increased their repertoire of
nutrients they’ve taken the strategy of
teaming up with an unrelated organism
the process is called sin trophy which
literally means feeding together the
strategy involves one bacterium breaking
down a complex chemical and feeding its
products to a methane producing
bacterium that use those to grow so how
does this work
these bacteria must seek out a partner
and they do this by recognizing
chemicals that are located on the
outside of the cells of the other
organism of the other bacterium and
swimming towards it this bacterium must
be close together to growth centrally
there are two strategies in one case the
close proximity is required for these
bacteria to most efficiently exchange
nutrients alternatively these bacteria
can just exchange electrons they do this
using what we call electrically
conductive nanowires
these are filaments made up of proteins
and metals and these cells are connected
by an electrically conductive network
that allows these cells to carry out the
complete conversion of complex organic
chemicals to carbon dioxide and methane
now this bacteria evolved in an
environment that was devoid of oxygen
and as a result these bacteria cannot
tolerate oxygen so methane production
only occurs in environments in which
oxygen is depleted this thing this
includes most of the locations that I’ve
talked about already room and wetlands
landfills tundra soils etc there’s
another part of this story at least from
an ecological perspective you may be
wondering whether all the methane that’s
produced actually makes it to the
atmosphere after all that methane
typically must pass through soils must
pass upwards typically through soils and
sediments that could potentially benefit
from the large amount of energy that’s
available and there is a large amount of
energy provided that there’s a suitable
oxidant available like oxygen in ocean
sediments and bottom waters that oxidant
is sulfate or nitrate but in soils and
wetlands oxygen is used here’s an
example of an amazing system where
methane is partially or fully oxidized
before it makes it to the atmosphere a
number of years ago I worked on a peat
bog here’s an example of a peat bog in
Latvia the one I worked on was called
Thoreau’s bog and the guy with the
mustache is one of my colleagues this is
in northern Massachusetts these peat
bogs are abundant they’re located in
northern areas northern part of the US
Canada Northern Europe they were formed
as glaciers moved south carving divots
in the ancient rock that’s present in
these locations as these holes filled up
with water this spagna Moss began to
grow and Spagna modifies its environment
decreasing the pH releasing acids
ensuring its survival in the system
because of the low ph of the water and
the relative lack of oxygen previous
years growth of the sphagnum Moss decays
quite slowly and as a result you end up
with literally thousands of years of
moss thousands of years of dead plant
material growing underneath the live
plant as this material of the case
methane is released methane is formed
and then released and actually gets
trapped up in the decaying plant
material serving to allow this entire
plant and dead plant emits and it
actually floats like a raft so you can
walk out on it and these people are
actually walking out on this layer of
this layer of sphagnum and other
materials that’s perhaps a meter or two
thick and there’s water underneath so as
the methane is produced underneath it
actually moves upwards and some of it
ends up being oxidized to carbon dioxide
some of it makes it up to the atmosphere
this same process occurs in wetlands all
around the world for example in the öyou
duck pond the upper part of the o-u duck
pond is an awesome wetland there’s
methane produced and then this methane
passes through plants that have the
potential to oxidize it perhaps an
interesting part of this story is that
the bacteria that convert the methane to
carbon dioxide are not located on the
outside of the plant as we would have
expected they’re actually located within
the plant cells these bacteria are
present in a symbiotic relationship with
this plant in which the plant provides
shelter for these bacteria and the
bacteria either provide nutrients or
energy to the plant
okay I’ve spoken about a number of
complex relationships
bacteria transforming methane are
involved in now that we were beginning
to understand the mechanisms for these
relationships we can begin to develop
technologies that take advantage of this
information perhaps the most obvious
potential application is in the energy
industry methane can be oxidized and in
nature this process involves the removal
of electrons a number of scientists have
developed what we call microbial
batteries or microbial fuel cells that
take advantage of microorganisms and
their mechanisms and their reactions to
produce energy from waste waters to
produce electricity from waste waters we
can think about similar process
developing a microbial battery to use
methane to generate electricity
this power could be used on site or it
could be pumped into the electrical grid
conversely electricity has the potential
to be used in a microbial system to
produce methane directly this could be
used when surplus power is available and
we will have surplus power as we expand
our solar power production I recently
obtained some funding from the National
Science Foundation to study novel
methane oxidizing bacteria and some
colleagues on this project are
interested in value-added products from
methane perhaps the most obvious example
the most obvious chemical is methanol
methanol is a liquid fuel that can be
much more easily transported and stored
than methane it also has a number of
industrial uses my colleagues are
interested in biodegradable polymers
these are chemicals that are produced by
bacteria that can be used to substitute
for plastics and do not last forever
when they’re released into the
environment these bacteria also have the
potential to produce proteins for either
medical or biotech
logical uses finally as we improve our
understanding of methane transformation
we can get a better idea a clear picture
of the factors that limit methane
release to the atmosphere environmental
scientists are always looking for better
ways to predict the flux of greenhouse
gases to the atmosphere so they can
determine what sort of changes in human
activities are needed to slow down
climate change thank you for your
attention
[Applause]
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