A team of researchers from Boston University, Harvard Medical School and Massachusetts Institute of Technology recently made a discovery that changes a long held paradigm about how bacteria move through soft gels. They showed that the bacterium that causes human stomach ulcers uses a clever biochemical strategy to alter the physical properties of its environment, allowing it to move and survive and further colonize its host.
The Proceedings of the National Academy of Sciences reports the findings in its most recent issue. Helicobacter pylori is a bacterium that inhabits various areas of the stomach where it causes chronic, low-level inflammation and is linked to gastric ulcers and stomach cancer. In order to colonize the stomach, H. pylori must cope with highly acidic conditions in which other bacteria are unable to survive. It is well known however, that the bacterium accomplishes this by producing ammonia to neutralize the acid in its surroundings. In addition, newly published research shows it does something else; it changes its environment to enable freer movement.
Acidic conditions within the stomach also work against the bacteria's ability to move freely. This is due to a protein called "mucin," a crucial component of the protective mucus layer in the stomach. In the presence of acid mucin forms a protective gel, which acts as a physical barrier that stops harmful bacteria from reaching the cell wall.
But, H. pylori increases the pH of its surroundings and changes this "mucin" gel to a liquid, allowing the bacterium to swim across the mucus barrier, establish colonies, attack surface cells and form ulcers.
"Bacteria 'swim' through watery fluids using their tails to propel them," said Boston University physicist Rama Bansil, who is currently on leave from BU, working as a Division of Materials Research program manager at the National Science Foundation. "But it was not obvious how they move through a s
|Contact: Bobbie Mixon|
National Science Foundation