In
the article, "Obstruction of Pilus Retraction Stimulates Bacterial Surface
Sensing," a group of interdisciplinary researchers show that in the case
of the bacterium Caulobacter crescentus, a model organism that splits its life
between swimming and attaching to surfaces, physically blocking the retraction
of its pili triggers the attachment to surfaces. Pili are ubiquitous microbial
appendages that many types of bacteria possess. During their study, the
scientists found a new technique to observe and film Caulobacter crescentus
pili undergoing dynamic cycles of extension and retraction. They were also able
to measure the forces exerted by the retraction of these nanometric tentacles
and noticed that within seconds of contact with a surface the cycles ceased.
This impediment of the retraction of the pilus coincided with the excretion of
the adhesive holdfast, a chemical glue required for firm attachment. Therefore,
bacteria need the resistance to pilus retraction that occurs upon contact with
a surface in order to sense surfaces and commit to a tighter adherence.
Therefore, bacteria need the resistance to pilus retraction that occurs upon
contact with a surface in order to sense surfaces and excrete the glue that
makes them firmly adhere.
Understanding
this mechanism of surface sensing in Caulobacter crescentus "might help us
understand how other bacteria sense surfaces and control their growth, either
to improve it in the case of good bacteria, used for instance in bioreactors,
or curb it as in the case of hospital pathogens growing on medical
catheters," said Dr. Nicolas Biais, Assistant Professor of Biology at
Brooklyn College and The Graduate Center of the City University of New York
(CUNY).
See:
Posted by Dr. Tim Sandle
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