Tuesday, November 10, 2009

Travel Secrets of Ulcer Causing Bacteria Revealed

Filed under: in the news...

A team from Boston University, MIT, and Harvard discovered how the H. pylori bacteria penetrate the stomach mucus to cause ulcers in the lining.

H. pylori secretes the enzyme urease, which interacts with urea in the stomach to produce ammonia--the ammonia is what neutralizes the acids in the immediate environment. The less-acidic environment de-gels the mucin, allowing the microbe to travel through it using standard, flagella-based locomotion, much like other swimming bacteria.

To confirm their findings, the researchers placed H. pylori into an acidic mucin gel in a laboratory setting. While its flagella moved, the organism could not. After the microbes secreted urease and acidity diminished, the microbes were able to forge through the gel.

Bansil and her colleagues next want to understand the progress of H. pylori-related diseases, particularly in the context of living hosts. The team is planning to work on new imaging techniques that may reveal even greater detail about the organisms and how they inflict damage on the human body.

H. pylori bacterium stuck in a mucin gel at pH4. The flagella rotate but the bacterium does not move freely. But it gains motility as it increases the pH level of the mucin:

This video clip shows H. pylori bacteria moving around in a mucin solution at pH 6. The higher pH level means the mucin is less solid and allows greater movement for the bacteria:

Abstract in PNAS: Helicobacter pylori moves through mucus by reducing mucin viscoelasticity ...

Read on from the National Science Foundation: How Bacteria Get Past Our Defenses ...

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