The technique is based on the transmission of tiny electric current in a very thin film sample cell containing a colony of bacteria. The current produces electrolysis that changes the local pH level in the vicinity of the electrodes. The bacteria, uncomfortable with the changes in pH, swim away from the electrodes and ultimately congregate in the middle of the experimental cell. Concentrated bacteria form self-organized swirls and jets resembling vortices in vigorously stirred fluid.
The method, which is suitable for flagellated bacteria such as E. coli, Bacillus subtilis, among many others, relies on the ability of bacteria to swim toward areas of optimal pH level. The bacteria live in an environment of a specific pH level, so that an increase or decrease of pH stimulates the bacteria to avoid areas of non-comfortable pH and swim in the direction of pH gradient. The researchers used an electric current to create a controlled deviation of the pH levels from the bulk values. Since only living bacteria respond to the pH stimulation, using this method can separate living and dead cells or bacteria with different motility.
The device, capable to change the thickness of a film from 1mm to 1 micron (with accuracy of 5 percent) and control the position of electrodes, is intended to separate and concentrate small quantities of living and dead microorganisms in confined spaces. It can be used for the purposes of express bioanalysis, diagnostic and identification of small bacterial samples, and separation sicken/live cells. A patent for the device is currently pending.
“Using this method, our research succeeded in dramatically increasing the concentration of microorganisms in tiny fluid drops and films. Unlike traditional centrifuging techniques, the new approach allows selective concentration of healthy cells,” said Andrey Sokolov, Ph.D. student from Illinois Institute of Technology and contributor to the research.
In addition to the development of the device used in the experimentation, research findings uncovered the explanation for the long-standing fundamental questions on the properties of collective and organized motion in the systems of interacting self-moving objects. Besides swimming bacteria, other examples include bird flocks, fish schools, motor proteins in living cell, and even swarms of communicating nano-robots.
“We have presented experimental studies of collective bacterial swimming in thin fluid films where the dynamics are essentially two-dimensional and the concentration can be adjusted continuously,” explained Igor Aronson, physicists at Materials Science Division, Argonne National Laboratory. “Our results provide strong evidence for the pure hydrodynamic origin of collective swimming, rather than chemotactic mechanisms of pattern formation when microorganisms just follow gradients of a certain chemical, such as nutrient, oxygen, or other.”
Detailed results of these findings have been published in Physical Review E and in Physical Review Letters.
Funding for this research was provided by the U.S. Department of Energy's Office of Basic Energy Science.
The nation's first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America's scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
For more information, please contact Sylvia Carson (630/252-5510 or firstname.lastname@example.org) at Argonne.
Sylvia Carson | alfa
Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery
20.01.2017 | GSI Helmholtzzentrum für Schwerionenforschung GmbH
Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences