Ask A Scientist© Molecular Biology Archive

name         Borna
status       student
age          14

Question -   How can a bacteria survive in a stomach and keep eating
it's tissue if the Ph of a stomach is 2? If it is
that way how come it can be treated with medications?
 
There are only few bacteria specialized to survive in
the stomach. For most others, the stomach is a real
bottle neck, and most will die when they stay in it
too long, or when the pH is too low (too acid). Don't
forget, however, that food particles can temporary
increase the pH, so that bacteria can 'sneek through'
with a meal. That is how food-borne pathogens reach
the intestines where they're fine.

The few bacteria that can survive in the stomach
produce specific enzymes that increase the pH around
them. Helicobacter pylori is the only example proven
to date to live preferentially in the stomach. The
enzyme they produce is Urease. They can survive long
enough to reach the epithelial cells that line the
stomach, and they live in the niches between these
cells. The pH of such niches is pretty neutral. So
although they can survive the acidity, they rather get
away from it.

The medications you are prescribed to get rid of your
Helicobacter (which can cause gastric ulcers) are
antibiotics. They have specific antibacterial
activity, and kill the bacteria without doing harm to
the stomach tissue. These antibiotics are acid
resistant.

Dr. Trudy Wassenaar
Curator of the Virtual Museum of Bacteria
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Bacteria are the most diverse and adaptable of the living organisms.  They
have been found in the Dead Sea, polar ice and in the geysers at Yellowstone.
  The bacteria that live in the stomach are adapted to live there and 
 probably
couldn't live a  higher pH.  There are antibiotics that can treat them.
Van Hoeck
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