Braff separating the good from the bad in bacteria


October 24, 2013

There are good bacteria and there are bad bacteria — and sometimes both coexist within the same species.  However, determining whether a bacterium is harmful typically requires growing cultures from samples of saliva or blood — a time-intensive laboratory procedure.  Now MIT researchers have developed a new microfluidic device that could speed the monitoring of bacterial infections associated with cystic fibrosis and other diseases.

The new microfluidic chip is etched with tiny channels, each resembling an elongated hourglass with a pinched midsection.  Researchers injected bacteria through one end of each channel, and observed how cells travel from one end to the other.  The cells were propelled by a technique called dielectrophoresis, in which voltage exerts a force on a particle.  But depending on the cells’ exterior composition, or phenotype, they either passed through the channel’s narrow section or were trapped at the opening.

Cullen Buie, the Mitsui Career Development Assistant Professor of Mechanical Engineering at MIT, says a bacterium’s reaction to voltage serves as a “fingerprint” for its phenotype, which in turn is a clue to how virulent that particular bacterium can be.  Buie, MIT graduate student William Braff, and colleagues Korneel Rabaey at Ghent University, in Belgium, and Dana Willner and Phil Hugenholtz at the University of Queensland, in Australia, have published their results in the journal PLOS ONE. Continue reading the article on MIT News.  Photo by Bryce Vickmark.

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