A few of the highly skilled microbes Jared Leadbetter is studying, and the factory in which they work.

If
you’ve had to deal with termites in your house, you probably hate their
guts. But not Jared Leadbetter. He loves termites, especially their
guts!

“It
turns out termites do something we’d like to do,” said Leadbetter, a
microbiologist at Caltech. That something is turning wood into biofuel,
and doing it at a nice, civilized temperature, pressure and acidity
level.

But
what Leadbetter is after isn’t really the biofuel termites use to power
their daily functions, it’s the substance they convert wood into on the
way to forming what they ultimately use for energy—an intermediate
substance called “pyruvate.”

He says pyruvate is to chemistry what a major airline hub is to travel.

“If
you can get to Chicago O’Hare, you may not want to go to La Crosse, but
it’s a pretty short flight to get to Lansing and a pretty short flight
to get to Fort Wayne and some of these other local airports,” he said.
“Termites are basically getting us to Chicago. And then they go to La
Crosse and we want to go somewhere else, but we actually know how to get
to all those regional airports from Chicago.”

That
is, we know how to make lots of useful products from pyruvate. But we
don’t know how to make pyruvate from wood, or from woody plant materials
like rice hulls, corn cobs and switchgrass.

So how do termites make that critical journey to pyruvate? They have friends in the right places.

“Termites
don’t digest wood by themselves,” Leadbetter said. “In fact, if you
eliminate the microbes from their guts, they are unable to digest wood
at all.”

It takes guts

According
to the microbiologist, there are hundreds of species of microbes in
termite guts found nowhere else in nature. “Every new generation of
termite acquires its microbes from the previous generation,” Leadbetter
said. “The insect and its microbes are a system that has been refined by
100 million years of evolution.” They work together to dismantle wood
into its components, extract the sugars, and ferment them into something
the termite can use for energy.

And
they do it very efficiently, with little adverse effect on the
environment—unless you count your house collapsing, if that’s what they
happen to be using as raw material. “A lot of termites are
desert-adapted, so they are degrading wood when water is at a premium,”
Leadbetter said. “Well, we live in a society where water is at a
premium.”

Also,
unlike some of our fellow creatures (I’m talking to you, cows),
termites process their food into energy without producing copious
amounts of methane, which is not only embarrassing in social situations,
but also a potent greenhouse gas. “Domestic animals and rice paddies
are major sources of methane globally,” Leadbetter said. “A cow can lose
up to about 20% of the electrons in each mouthful of food as methane
and termites often lose less than 2%.” He said that understanding why
cows and rice paddies produce so much methane while termites produce so
little may one day enable us to significantly reduce the amount of this
gas that is released into the atmosphere and heats up the planet.

But
what really drives Leadbetter is an intense distaste for wasting
resources. Take sugarcane, which is one of the crops currently processed
into ethanol and used as a biofuel. “Between 50 and 70% of the energy
in every sugar cane is not in the sugar that you squeeze out of it,” he
said. He explained that most of that energy remains in a woody waste
product called “bagasse,” much of which winds up in landfills. “That’s
tremendous potential,” Leadbetter said. “Anytime you could improve your
yield by two, that is a pretty interesting idea.”

Similar
stories can be told about corncobs, rice hulls, and other agricultural
waste. “We have plant material, sometimes that we are already burning as
an energy source, and maybe we could do something else with it that
doesn’t involve dirty combustion,” he said.

Stayin’ alive

According
to Leadbetter, the termite holds the key to unlocking all of this
potential. But understanding how to do it won’t be easy.

People
have enlisted the help of microbes before, but never with this degree
of complexity. “For 6,000 years,” he said, “we’ve been making beer, wine
and bread using yeast,” which is a single-cell organism in the kingdom
of fungi. “But as we move into this next stage of wanting to turn more
complex materials into something we might use, it’s not going to be an
organism. It’s not going to be 10 organisms. It’s going to be a
microbial community involving hundreds of organisms and thousands of
enzymes.” He estimated that it could take from 10 to 25 years before we
understand the process well enough to harness it.

Currently,
scientists are having a tough time just keeping the microbes alive
outside of a termite. “The major challenge remains being able to grow
these organisms which only grow in a termite and say, well let’s add one
other place on Earth where they’ll grow. Let’s say in this test tube in
the laboratory,” Leadbetter said. He’s had some success with a
half-dozen or so of these microbes, but there are several hundred
involved in the process. “We have to ask, why is it we can’t grow them?”
he said. “It’s because they are in some ways dependent on each other.”

Unraveling
the intricate inner workings of the termite has occupied Leadbetter for
years, and promises to do so for many years to come. But even his
fascination with termites has its limits. “I love them,” he said. “But
they say you shouldn’t bring your work home with you.”

A world in a droplet

The
mysterious world Leadbetter is investigating occupies about a
microliter of fluid inside the termite gut. That’s 300,000 times less
than a fluid ounce. It’s home to hundreds of unique species of microbes,
doing things that scientists don’t yet understand.

“I
like to say that I work in a miniature Alice in Wonderland,” Leadbetter
said. “It’s this teeming, churning craziness—this crazy zoo of all
these different organisms. They come in all sorts of wild shapes and
sizes and they’re doing all sorts of different interesting things.”

And
similar micro-worlds are everywhere. “We can go for a walk in a
rainforest in Costa Rica, and that’s a fascinating place,” Leadbetter
said. “But there are also these little miniature rainforests, if you
will, all around us that we may not even notice.

“People
will talk about what’s in a gram of soil. Well, a gram has lots of
microliter environments in it. So even one gram of soil might be a
Manhattan of complexity. And to understand the little neighborhoods is
going to be a very complex process.”

Source: NASA Jet Propulsion Laboratory