Living in extreme conditions requires creative adaptations. For certain species of bacteria that exist in oxygen-deprived environments, this means finding a way to breathe that doesn’t involve oxygen. These hardy microbes, which can be found deep within mines, at the bottom of lakes, and even in the human gut, have evolved a unique form of breathing that involves excreting and pumping out electrons. In other words, these microbes can actually produce electricity.
Bacteria that produce electricity do so by generating electrons within their cells, then transferring those electrons across their cell membranes via tiny channels formed by surface proteins, in a process known as extracellular electron transfer, or EET.
For the past 10 years, his group has been building microfluidic chips etched with small channels, through which they flow microliter-samples of bacteria. Each channel is pinched in the middle to form an hourglass configuration. When a voltage is applied across a channel, the pinched section—about 100 times smaller than the rest of the channel—puts a squeeze on the electric field, making it 100 times stronger than the surrounding field. The gradient of the electric field creates a phenomenon known as dielectrophoresis, or a force that pushes the cell against its motion induced by the electric field. As a result, dielectrophoresis can repel a particle or stop it in its tracks at different applied voltages, depending on that particle’s surface properties. Bacteria that were more electrochemically active tended to have a higher polarizability.
“We have the necessary evidence to see that there’s a strong correlation between polarizability and electrochemical activity,” Wang says. “In fact, polarizability might be something we could use as a proxy to select microorganisms with high electrochemical activity.”
Wang says that, at least for the strains they measured, researchers can gauge their electricity production by measuring their polarizability—something that the group can easily, efficiently, and nondestructively track using their microfluidic technique.
Collaborators on the team are currently using the method to test new strains of bacteria that have recently been identified as potential electricity producers.
“If the same trend of correlation stands for those newer strains, then this technique can have a broader application, in clean energy generation, bioremediation, and biofuels production,” Wang says.
News Source: https://techxplore.com
Post time: Jan-18-2019