How bacteria can move toward light has always
been a mystery. But now, a team of researchers
found that each organism uses its entire body
to refract and focus light…
you know, like your eyeballs.
I often wonder, “How do those monstrous
slimes or gelatinous cubes move toward me
in a dungeon? They don’t have eyes!” After
300 years of research, science has finally
found the answer: the world’s smallest example
of an eye.
We already knew that certain cyanobacteria
move towards light sources, like say a torch,
but we didn’t know how they detected it.
Thanks to a team of British and German researchers
whose work was published in the journal “eLife”
in February of 2016, we now know that while
cyanobacteria’s biological structures are
different from ours, the physical principles
for how they sense light are actually quite
similar to how we humans do it.
But first, what the heck are cyanobacteria?
Well they’re single-cell, blue-green bacteria
that’re pretty common in underwater environments.
You know that slippery, green film you find
on underwater rocks? This study specifically
looked at a species called synechocystis,
found in freshwater lakes and rivers.
By testing a mutant version of this bacteria
- that's right I said mutant - that accumulates
green fluorescent proteins, the researchers
were able to learn that each cell body acts
like a lens. Light hits its spherical surface
and then refracts on the other side of the
cell with intense focus. This triggers the
cells’ photoreceptors, which cue the cell
to steer towards the light.
Now the moving… that’s the creepy part.
The bacteria each grow tiny little tentacles,
called “pili,” that reach out toward the
light. The pili tentacles only form on the
side facing the light source, attaching to
the surface they’re on and then retracting
to pull the bacteria along.
While the light refraction principle is essentially
similar to human vision, a synechosystis cell
is about three thousandths of a millimetre
across -- half a billion times smaller than
the human eye. So its resolution is low and
can only perceive blurred outlines of objects.
Kind of like when I take my glasses off.
Is this evidence of an evolutionary connection
between bacteria and people? Do other bacteria
see the same way? And how will this help me
in my future battles against gelatinous cubes
and elder black puddings? Let us know what
you think. And to keep up with the latest
science research (and my fate in the “Slave
Pits of the Undercity”), make sure to visit
us at now.howstuffworks.com every day.
