"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!
Smallest transistor worldwide switches current with a single atom in solid electrolyte
17.08.2018 | Karlsruher Institut für Technologie (KIT)
Protecting the power grid: Advanced plasma switch for more efficient transmission
17.08.2018 | DOE/Princeton Plasma Physics Laboratory
There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.
The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
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20.08.2018 | Life Sciences
20.08.2018 | Information Technology