Monitoring the isolated vibrations of E. coli on a cantilever allows scientists to assess colony health in real time – a potential new screen for antibiotics and cancer drugs
A team of researchers at Boston University and Stanford University School of Medicine has developed a new model to study the motion patterns of bacteria in real time and to determine how these motions relate to communication within a bacterial colony.
L. Li and C. Lissandrello / Boston University
Illustration of a microcantilever sensor with E. coli bacteria attached and a close-up illustration of a single bacterium (inset). The motion of the bacteria couple to the cantilever and the cantilever motion is detected using the optical beam deflection technique.
The researchers chemically attached colonies of Escherichia coli bacteria to a microcantilever – a microscopic beam anchored at one end, similar to a diving board – thus coupling its motion to that of the bacteria. As the cantilever itself isn’t doesn’t generate any vibrations, or ‘noise,’ this allowed the researchers to monitor the colony’s reactions to various stimuli in real time.
“When they die, they stop moving, so it’s a good way to measure the effectiveness of an antibiotic,” said Kamil Ekinci, an associate professor at Boston University. He and fellow researchers describe their work in the journal Applied Physics Letters, which is produced by AIP Publishing. “You know more or less immediately that they’re dead.”
The traditional method of assessing a bacteria’s antibiotic susceptibility– culturing bacteria on agar plates infused with antibiotics – is quite time-consuming in comparison, and can take up to a day to produce results.
“Here in this system – down to a couple hundred of bacteria – we’re able to see their responses to external stimuli such as drugs,” said Utkan Demirci, an associate professor at Stanford University School of Medicine. “This also potentially applies to other types of cells, such as drug resistance in cancer.”
While cantilevers have been used before to characterize cellular mechanics, Ekinci and Demirci bring a new approach to look at cellular movement and noise in natural systems, hoping to eventually develop a disposable microfluidic chip.
“It’s a new direction for tool development,” Demirci said. “It could allow us to address some interesting biological questions in the antibiotic resistance and evolution space.”
Ekinci also found that when the amplitude of the bacteria’s random movements was plotted against their frequency, a distinct, familiar pattern began to emerge.
“We saw that the fluctuations were focused at certain frequencies – they weren’t like white noise,” Ekinci said. Not quite white, but rather, something closer to pink.
1/f-type noise, also known as pink-like noise, is a recurring pattern in which the power spectral density of a signal is inversely proportional to its frequency. This occurs within a wide variety of systems, including biological processes such as the random firing of neuron channels and the electrocardiogram of a heart’s rhythms, as well as in mechanical processes such as background noise in electronic devices and pitch progression in classical music.
“We think that there are several different time scales in the motion of these bacteria, and when you look at them collectively, you see 1/f-type behavior,” Ekinci said.
In addition to the long-term goal of creating smaller, portable sensors, future work includes identifying the precise structural sources of vibrations, in order to develop a quantitative physical model of the noise and better understand the bacterial communication pathways.
“I want to make this more quantitative and determine the sources of these noises,” Ekinci said. “I think this could be a useful tool for doing some fundamental studies.”
The article, "Nanomechanical motion of Escherichia coli adhered to a surface," is authored by C. Lissandrello, F. Inci, Utkan Demirci and Kamil L. Ekinci. It will appear in the journal Applied Physics Letters on September 16, 2014. After that date, it can be accessed at:
ABOUT THE JOURNAL
Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: http://apl.aip.org
Jason Socrates Bardi
Jason Socrates Bardi | newswise
Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State
What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy