[Microbiology] Helicobacter pylorii

[Fabrizio]

Hi,
        the Helicobacter pylorii changes its form between spiral and coccoid 
one depending on enviromental condition 
http://www.sodbrennen-welt.de/science/1994/1994_7524304.htm.

This helps the bacter to survive but I don't understand why, what are the 
advantages in changing the form? How does it happens biochemically?

Any suggestion?

Thank you,
Fabrizio