Researchers at the University of Warwick have found bacteria can be detected in minutes by zapping them with electricity.

Scientists at the university in the United Kingdom discovered healthy bacteria cells and those inhibited by antibiotics or UV light show different electric reactions. When zapped with an electrical field, live bacteria absorb dye molecules causing the cells to light up so they can be counted. Bacillus subtilis and E. coli were used as model organisms.

Testing commercial products for bacterial contamination can take days. During this time, they can cause significant numbers of illnesses and infections can become life threatening if not identified and treated appropriately.

Detect contamination in manufacturing
The researchers’ findings, published in Proceedings of the National Academy of Sciences of the United States of America, could lead to development of medical devices that can rapidly detect live bacterial cells, evaluate the effects of antibiotics on growing bacteria colonies, or identify different types of bacteria and reveal antibiotic-resistant bacteria. One target is quality control in the water, pharmaceutical, food, and beverage industries.

James Stratford, from the School of Life Sciences and spinout company Cytecom, said “the system we have created can produce results which are similar to the plate counts used in medical and industrial testing but about 20 times faster. This could save many people’s lives and also benefit the economy by detecting contamination in manufacturing processes.”

Scientists showed bioelectrical signals from bacteria can be used to determine if they are alive or dead. The approach uses membrane-potential dynamics and electrical stimulation to differentiate between incapacitated and viable cells.

The team developed an experimental tool to study the relation of bacterial electrical signaling. Using it combined with time-lapse microscopy, they showed live and inhibited cells respond to electrical stimulation in opposite directions. A 2.5-second electrical stimulation caused hyperpolarization in unperturbed cells while inducing depolarization in inhibited cells.

Creation of start-up firm
Findings offer an approach for rapid detection of proliferative bacteria without observation of actual proliferation or time-consuming calibrations for bacterial species. It can detect proliferative cells within a minute after electrical stimulation.

Researchers founded a start-up company called Cytecom. The firm has been awarded a grant from Innovate UK, a national funding agency, which means devices could be available to researchers and businesses shortly.

The team combined biological experiments, engineering and mathematical modelling.

“This work demonstrates that bacterial electricity can lead to societally important technology, while at the same time gaining fundamental insights into our basic understanding of cells. The tool we developed can offer more opportunities by allowing experiments which were not possible to perform before,” said Munehiro Asally, assistant professor at the University of Warwick.