The ocean
floor and the ground beneath our feet are riddled with tiny
nanowires—1/100,000th the width of a human hair—created by billions of bacteria
that can generate electric currents from organic waste. In new research
published Aug. 17 in the journal Nature Chemical Biology, Yale researchers
describe how this hidden power grid could be activated with a short jolt of
electric field.
"We
live in an electric world," said Nikhil Malvankar, assistant professor of
molecular biophysics and biochemistry at the Microbial Science Institute at
Yale's West Campus and senior author of the paper. "The strength and
conductivity of these nanowires, coupled with the ability of bacteria to repair
themselves, could help create durable, self-healing, electronics out of living
cells."
In
environments without oxygen, the bacterium Geobacter "breathe" by
projecting tiny protein filaments called nanowires into bacterial communities
known as biofilms to dispose of excess electrons resulting from the conversion
of organic waste to electricity. But it has remained a mystery how these
bacteria, which stack themselves on top of each other like apartment
high-rises, send electrons over distances 100-times their size.
In
previous research, the team showed that nanowires comprised of a protein called
OmcS contained tiny metallic building blocks, or hemes, throughout their
length. OmcS transmits electricity. The new study found that when stimulated by
an electric field, the bacteria produce previously unknown nanowires of a
different, more efficient protein, OmcZ. It transmits electricity 1,000 times
more efficiently than OmcS.
Sibel Ebru
Yalcin, a research scientist at Yale's Microbial Sciences Institute, led this
work with graduate students J. Patrick O'Brien, Yangqi Gu and Krystle Reiss.
"Surprisingly,
nanowires can withstand and function in extreme acidic environments where most
proteins break down," Yalcin noted. "This provides a unique
opportunity to develop novel sensors and highly resilient materials."