Monday, October 28, 2013

Bizarre purple shiny mat in Kilauea cave is a new species of cyanobacteria

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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