Alapfogalmak
Magnetotactic bacteria can efficiently navigate through complex, obstacle-filled environments by adapting their swimming behavior to the strength of the external magnetic field.
Kivonat
The study investigates how magnetotactic bacteria, which align and swim along magnetic field lines, navigate through microfluidic channels that mimic the complex, obstacle-filled environment of their natural sediment habitat.
The researchers first characterized the sediment samples using micro-computer tomography and used the data to construct microfluidic channels with irregular obstacle arrays. They then studied the swimming of magnetotactic bacteria through these channels under different magnetic field strengths.
The experiments showed that the bacteria's throughput through the obstacle channels was highest at an intermediate magnetic field strength, comparable to the Earth's magnetic field. At weaker or stronger fields, the throughput was reduced.
Extensive computer simulations, using an active Brownian particle model parameterized based on the experimental data, provided insights into the underlying mechanisms. The simulations revealed that at strong magnetic fields, the bacteria get trapped in corners formed by overlapping obstacles, as they struggle to swim against the field direction required to escape these traps. At weak fields, the bacteria's motion becomes effectively diffusive, reducing their ability to navigate the obstacle array efficiently.
The results suggest that magnetotactic bacteria have evolved magnetic properties adapted to the Earth's magnetic field, balancing their directed motion along the field lines with the ability to transiently swim against the field direction when needed to escape traps in their complex natural environments.
Statisztikák
The sediment sample consists of 61% sand and 39% water.
The mean sand grain diameter is 46 μm.
The mean water gap size is 43 μm.
Idézetek
"Magnetotactic bacteria are microorganisms that form chains of nanomagnets and that orient in Earth's magnetic field."
"We hypothesize that over the course of evolution, magnetotactic bacteria have thus evolved to produce magnetic properties that are adapted to the geomagnetic field in order to balance movement and orientation in such crowded environments."