The
antimicrobial properties of silver have been known for centuries. While it is
still a mystery as to exactly how silver kills bacteria, University of Arkansas
researchers have taken a step toward better understanding the process by
looking at dynamics of proteins in live bacteria at the molecular level.
Traditionally,
the antimicrobial effects of silver have been measured through bioassays, which
compare the effect of a substance on a test organism against a standard, untreated
preparation. While these methods are effective, they typically produce only
snapshots in time, said Yong Wang, assistant professor of physics and an author
of the study, published in the journal Applied and Environmental Microbiology.
Instead,
Wang and his colleagues used an advanced imaging technique, called
single-particle-tracking photoactivated localization microscopy, to watch and
track a particular protein found in E. coli bacteria over time. Researchers
were surprised to find that silver ions actually sped up the dynamics of the
protein, opposite of what they thought would happen. "It is known that
silver ions can suppress and kill bacteria; we thus expected that everything
slowed down in the bacteria when treated with silver. But, surprisingly, we
found that the dynamics of this protein became faster."
The observation of DNA
separation
caused by silver ions came from earlier work that Wang and colleagues had done
with bent DNA. Their approach, now patent pending, was to put strain on DNA
strands by bending them, thus making them more susceptible to interactions with
other chemicals, including silver ions.
The
National Science Foundation-funded study validated the idea of investigating
the dynamics of single proteins in live bacteria, said Wang, an approach that
could help researchers understand the real-time responses of bacteria to silver
nanoparticles, which have been proposed for fighting against so-called
"superbugs" that are resistant to commonly prescribed antibiotics.
"What
we want to do eventually is to use the new knowledge generated from this
project to make better antibiotics based on silver nanoparticles," said
Wang.
Posted by Dr. Tim Sandle, Pharmaceutical Microbiology Resources (http://www.pharmamicroresources.com/)
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