A team of MIT and Brown University researchers have developed a microfluidic device that can separate bacteria, based on whether they have right and left handed helical-shaped flagella. This research can have implications for easy and quick separation of all kinds of chemicals that exhibit chirality.
The National Science Foundation explains:
While single-celled bacteria do not have hands, their helical-shaped flagella spiral either clockwise or counter-clockwise, making opposite-turning flagella similar to human hands in that they create mirror images of one another.
This two-handed quality is called chirality, and in a molecule, it can make the difference between healing and harming the human body.
“This discovery could impact our understanding of how water currents affect ocean microbes, particularly with respect to their ability to forage for food, since chiral effects make them drift off-course,” said Roman Stocker, a marine scientist at MIT and lead investigator on the research project. “But it is also important for several industries that rely on the ability to separate two-handed molecules.”
Stocker and graduate student Marcos, along with co-authors Henry Fu and Thomas Powers of Brown University, published their findings in the April 17 issue of the journal Physical Review Letters.
One of the best-known instances of a chiral molecule causing widespread harm occurred in the 1950s, when the drug thalidomide was given to pregnant women to prevent morning sickness.
One naturally occurring form–or isomer–of thalidomide reduces nausea; the other causes birth defects. In another commonly used chiral drug, naproxen, one isomer is analgesic; the other causes liver damage.
In their paper, the researchers describe how they designed a microfluidic environment–a device about the size of an iPod nano that has channels containing water and bacteria–to create a “shear” flow of layers of water moving at different speeds.
In their tests, Stocker and Marcos used a non-motile mutant of the bacterium Leptospira biflexa, whose entire body has the shape of a right-handed helix.They injected the Leptospira into the center of the microfluidic device and demonstrated that the bacteria drift off-course in a direction dictated by their chirality.
The researchers also developed a mathematical model of the process, and are implementing this new approach to separate objects at molecular scales.
One of the best-known instances of a chiral molecule causing widespread harm occurred in the 1950s, when the drug thalidomide was given to pregnant women to prevent morning sickness.NSF press release: “Two-handed” Marine Microbes Point to New Method for Isolating Harmful Forms of Chemicals …
Images: Top: The device used to discover new information about marine bacteria. Side: The bacterium Leptospira biflexa (Source: MIT)