"Escherichia coli (E. coli) and some other pathogenic bacteria with flagella interact with the flow of liquid when they are near a surface," said Hür Köser, assistant professor of electrical engineering at Yale and the study's senior author, who has collaborated with a diverse team of scientists for this study.
"Each cell normally has two to six flagella that can rotate together as a bundle and act as a propeller to drive the cell forward. Away from any boundaries, the cells swim in a straight line, but near a surface, opposing forces of flow and bacterial forward motion cause the bacteria to continuously swim to one side — to the left." The study determined that swimming "to the left" is a hydrodynamic process that is fundamentally related to the way the cells propel themselves in this manner.
Köser and his colleagues show that this phenomenon allows flagellated bacteria, such as E. coli, to find crevices or imperfections on the surface, get trapped, and swim upstream. This allows the bacteria to eventually locate large reservoirs with richer sources of food and better conditions for multiplying.
"We think that upstream swimming of bacteria may be relevant to the transport of E. coli in the urinary tract," said Köser. "It might also explain the high rates of infection in catheterized patients and the incidence of microbial contamination at protected wellheads. To our knowledge, this is the first time that a natural propensity to swim upstream has been discovered and described in bacteria."
To study the hydrodynamics of these bacteria in a flow environment, Köser's team constructed microfluidic devices using soft lithography. Inside the devices they set up various flow patterns to observe the bacteria in channels that were only 150 or 300 microns wide and between 50 and 450 microns deep. They were able to observe how the bacteria moved at a wide range of flow rates — between 0.05 and 20 microliters per minute.
Janet Rettig Emanuel | EurekAlert!
Basque researchers turn light upside down
23.02.2018 | Elhuyar Fundazioa
Attoseconds break into atomic interior
23.02.2018 | Max-Planck-Institut für Quantenoptik
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
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23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy