Cyanobacteria, which have sometimes confusingly and
inaccurately been called blue-green algae, are cool critters.
To find a new species to science, in a genus that is
only represented by one other species in the world, is cooler still.
And to find it in a hot, 100-year-old volcanic cave on
active Kilauea volcano, well, that's so cool it's downright polar.
University of Hawai`i researchers are reporting they found
the primitive life form on a film of biological material growing on the rock
wall of a Kilauea cave a few hundred feet from Halema`um a`u. To get into it,
they had to back feet first through a small entrance into the cave, whose floor
radiated heat at 90 degrees Celsius or 190 degrees Fahrenheit.
(Image: The cyanobacteria mat on Kilauea cave wall. Photo courtesy Stuart Donachie, UH.)
They found a glistening purple mat of moist stuff, growing in
very low light on the cave wall. When they ran its genetics, they found it fits in a genus of
cyanobacteria that wasn’t described until 1974 and has only one other species
in it. That one was found in Switzerland on limestone rock, while this one was
on basalt. And genetic work showed the two had diverged from each other 280
million years ago.
Why should we care about cyanobacteria? We wouldn’t exist
without them. They are largely responsible for much of the oxygen in our
atmosphere. Some varieties fix nitrogen, creating nutrients for plants.
They are some of the earliest life forms ever identified on
Earth. They’re different from many others in that their cells have no nucleus,
making them procaryotes like bacteria. By contrast, humans and other animals, insects,
fungi and all plants are eucaryotes: they have their genetic material encased
in nuclei within their cells.
“Cyanobacteria are among the most diverse and successful
microbes on Earth. As pioneers of oxygenic photosynthesis they permanently
changed Earth's atmosphere by emitting gaseous diatomic oxygen, paving the way
for the evolution of aerobic metabolism,” says a paper in the journal PLOS One,
“Cultivation and Complete Genome Sequencing of Gloeobacter kilaueensis sp. nov., from a Lava Cave in Kīlauea
Caldera, Hawai'i.”
The paper’s authors are Jimmy H. W. Saw, Michael Schatz, Mark
V. Brown, Dennis D. Kunkel, Jamie S. Foster, Harry Shick, Stephanie
Christensen, Shaobin Hou, Xuehua Wan, and Stuart P. Donachie.
As the article title suggests, they’re proposing naming the
new species Gloeobacter kilaueensis sp.
nov. (sp. nov. simply stands for “new
species.”)
A colony of these new cyanobacteria is purple in color, and
smooth and shiny. It has a gel or mucous-looking surface, said co-author
Stuart Donachie. He said it’s a unique discovery.
"It’s a great find because both species represent an
entire taxonomic order distinct from the other 7,500 known cyanobacteria
species. They lack the photosynthetic membranes that are found in all those
7,500 species, which means they are also the most primitive known cyanobacteria,”
said Donachie an associate professor in the Department of Microbiology at the University
of Hawai`i’s College of Natural Sciences.
So how did this cyanobacterium get into a hot, young Kilauea
cave?
“That’s a question we get asked all the time. It is a
question we could not answer and have not answered,” Donachie said.
The most likely answer, he figures, is that it blew in on
the wind. And not from a Switzerland colony.
That suggests there are, somewhere on the planet, other,
undiscovered cyanobacteria colonies in the Gloeobacter genus, one of which was
the source for Gloeobacter kilaueensis.
© Jan TenBruggencate 2013
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