Dr. Jonathan Olson, 919/515-7860 or email@example.com
News Services, 919/515-3470.
Find that Ulcer-Causing Pathogen Uses Hydrogen for Energy
a groundbreaking study, a North Carolina State University
microbiologist has discovered that the bacteria associated
with almost all human ulcers - one that is also correlated
with the development of certain types of gastric cancer
in humans - uses hydrogen as an energy source.
The finding is novel because most bacteria use sugars
and other carbohydrates to grow, says Dr. Jonathan Olson,
assistant professor of microbiology at NC State. The
human pathogen Helicobacter pylori does not.
one has ever suspected hydrogen to be an energy source
for pathogens," Olson said. "Now we have a
whole new target for antibiotics for this particular
research is described in a paper published in the Friday,
Nov. 29 edition of Science.
study was performed at the University of Georgia, where
Olson was a member of the research faculty before joining
the microbiology faculty at NC State this summer. Dr.
Robert J. Maier, a microbiologist at the University
of Georgia, is a co-author of the paper. The work was
supported by the Georgia Research Alliance.
pylori is only found in humans, Olson says. The
bacteria infects greater than 50 percent of the world's
population, and persists until it is treated. If left
untreated, the bacteria can give rise to ulcers and
two different kinds of cancer.
pylori contains an enzyme - hydrogenase - that uses
hydrogen as an energy source. "If we were to develop
a drug to inhibit the hydrogenase enzyme, we could eradicate
ulcers in humans," Olson says.
mice as a model, the scientists discovered that mice
stomachs contained more than enough hydrogen to support
the growth of H. pylori. The study showed that
mice stomachs contained 10 to 50 times more hydrogen
than the bacteria needs to grow.
when the scientists created a mutant strain of H.
pylori without hydrogenase, only 24 percent of these
mutants colonized in mice, as opposed to 100 percent
of the parent strain that was able to utilize hydrogen,
Olson says. The mutants that did colonize in mice also
had lower levels of bacteria, he says.
is a complicated enzyme that is not made by humans.
Olson says that finding an antibiotic that is specifically
targeted to inhibit the enzyme shouldn't be toxic to
other human enzymes. However, no compounds that specifically
inhibit hydrogenase currently exist, so the development
of such a drug will come later rather than sooner, Olson
not many bacteria use hydrogen to grow, Olson and Maier
are among a small fraternity of scientists who study
bacterial hydrogen utilization. Most of these bacteria
exist in hydrogen-rich environments, Olson says, mainly
in agricultural areas.
lab at NC State is presently studying a hydrogen-utilizing
bacteria that is the most common cause of food poisoning.
to editors: An abstract of the Science
Hydrogen as an Energy Source for Helicobacter pylori"
Authors: Jonathan W. Olson, North Carolina State
University; Robert J. Maier, University of Georgia
Published: Nov. 29, 2002, in Science
Abstract: The gastric pathogen Helicobacter
pylori is known to be able to use molecular hydrogen
as a respiratory substrate when grown in the laboratory.
We found that hydrogen is available in the gastric mucosa
of mice and that its use greatly increased the stomach
colonization by H. pylori. Hydrogenase activity
in H. pylori is constitutive but increased fivefold
upon incubation with hydrogen. Hydrogen concentrations
measured in the stomachs of live mice were found to
be 10 to 50 times as high as the H. pylori affinity
for hydrogen. A hydrogenase mutant strain is much less
efficient in its colonization of mice. Therefore, hydrogen
present in animals as a consequence of normal colonic
flora is an energy-yielding substrate that can facilitate
the maintenance of a pathogenic bacterium.