Scientists have recently sequenced the genome of a microbe that
processes carbon monoxide into hydrogen.
Take a pot of scalding water, remove all the oxygen, mix in a bit of
poisonous carbon monoxide, and add a pinch of hydrogen gas. It sounds
like a recipe for a witch's brew. It may be, but it is also the
preferred environment for a microbe known as Carboxydothermus
In a paper published in the November 27th issue of PLoS Genetics, a
research team led by scientists at The Institute for Genomic Research
(TIGR) report the determination and analysis of the complete genome
sequence of this organism. Isolated from a hot spring on the Russian
volcanic island of Kunashir, this microbe lives almost entirely on
carbon monoxide. While consuming this normally poisonous gas, the
microbe mixes it with water, producing hydrogen gas as waste.
As the world increasingly considers hydrogen as a potential biofuel,
technology could benefit from having the genomes of such microbes. "C.
hydrogenoformans is one of the fastest-growing microbes that can convert
water and carbon monoxide to hydrogen," remarks TIGR evolutionary
biologist Jonathan Eisen, senior author of the PLoS Genetics study. "So
if you're interested in making clean fuels, this microbe makes an
excellent starting point."
In sequencing the microbe's genome, Eisen and his collaborators
discovered why C. hydrogenoformans grows more rapidly on carbon monoxide
than other species: The bug boasts at least five different forms of a
protein machine, dubbed carbon monoxide deyhydrogenase, that is able to
manipulate the poisonous gas. Each form of the machine appears to allow
the organism to use carbon monoxide in a different way. Most other
organisms that live on carbon monoxide have only one form of this
machine. In other words, while other organisms may have the equivalent
of a modest mixing bowl to process their supper of carbon monoxide, this
species has a veritable food processor, letting it gorge on a hot spring
buffet all day.
"The findings show the continued value of microbial genome sequencing
for exploring the useful capabilities of the vast realm of microbial
life on Earth," says Ari Patrinos, director of the Office of Biological
and Environmental Research, part of the U.S. Department of Energy's
(DOE) Office of Science. DOE, which funded the study, is pursuing clean
Little was known about this hydrogen-breathing organism before its
genome sequence was determined. By utilizing computational analyses and
comparison with the genomes of other organisms, the researchers have
discovered several remarkable features. For example, the genome encodes
a full suite of genes for making spores, a previously unknown talent of
the microbe. Organisms that make spores have attracted great interest
recently because this is a process found in the bacterium that causes
anthrax. Sporulation allows anthrax to be used as a bioweopon because
the spores are resistant to heat, radiation, and other treatments.
By comparing this genome to those of other spore-making species,
including the anthrax pathogen, Eisen and colleagues identified what may
be the minimal biochemical machinery necessary for any microbe to
sporulate. Thus studies of this poison eating microbe may help us better
understand the biology of the bacterium that causes anthrax.
Building off this work, TIGR scientists are leveraging the information
from the genome of this organism to study the ecology of microbes living
in diverse hot springs, such as those in Yellowstone National Park. They
want to know what types of microbes are found in different hot
springs--and why. To find out, the researchers are dipping into the hot
springs of Yellowstone, Russia, and other far-flung locales, to isolate
and decipher the genomes of microbes found there.
"What we want to have is a field guide for these microbes, like those
available for birds and mammals," Eisen says. "Right now, we can't even
answer simple questions. Do similar hot springs, a world apart, share
similar microbes? How do microbes move between hot springs? Our new work
will help us find out."
The Institute for Genomic Research is a not-for-profit center dedicated
to deciphering and analyzing genomes. Since 1992, TIGR, based in
Rockville, Md., has been a genomics leader, conducting research critical
to medicine, agriculture, energy, the environment and biodefense.