By: Jessica Robertson
It is no secret that the high level
of pollution of our planet, from sources like car engines or even cigarettes,
is harmful. One particularly common contaminant, polycyclic aromatic hydrocarbons
(PAHs), is a toxic tar substance that is believed to be a cause of cancer.
These contaminants, and others, are often trapped in soil; PAHs, particularly,
were thought to be mostly immobile in soil, binding to soil particles and being
unable to dissolve in water. These qualities made clean up of contaminated soil
quite a challenge.
A new study shows, however, a way
to deal with these pesky contaminants. Some tiny microorganisms that do have
the ability to move, like the unicellular slipper-shaped ciliate Tetrahymena pyriformis, have the
surprising ability to take up the substance into the lipid layer of their cell
membrane and act as a shuttle to the PAHs. This method means a much faster
transport of the PAHs than the method of simple diffusion; furthermore, the
ciliates are still able to transport the PAHs when there is no fluid flow, a
situation where diffusion would be impossible.
Increasing the mobility of the PAHs
by ciliate transport can increase the exposure of the PAHs to bacteria that can
degrade them or to plant roots that can absorb them. These being the two main
methods of biological treatment of PAH-contaminated soil, introducing such micro-organisms to contaminated soil can speed up what used to be a lengthy
bioremediation process.
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