Sulfolobus/Saccharolobus

Dr. Stedman sampling  Sulfolobus  in the Rabbit Creek Hot Spring Area in Yellowstone National Park, United States, 2001

Dr. Stedman sampling Sulfolobus in the Rabbit Creek Hot Spring Area in Yellowstone National Park, United States, 2001

Hot Stuff

The genus Saccharolobus (formerly Sulfolobus), and related species, are acidothermophilic archaea that live in geothermal hot springs around the world, so their ideal living environment is in near-boiling sulfurous acid. In order to grow the most commonly used species in the Stedman Lab, S. solfataricus, cells are cultured in a rich media at pH 3.2. We grow the cultures in microaerophilic flasks in shakers set at around 75º C (167º F), and they love it! Different species vary slightly, but most Saccharolobus have a similar ideal pH and temperature. While most of the work in the Stedman lab looks at viruses, we do some work with our main host organism itself - Saccharolobus, and related species.

 

A fuzzy new friend

Eggs turned black from boiling in the Kuroyu Hot Spring      (source)

Eggs turned black from boiling in the Kuroyu Hot Spring (source)

Kuroyu Hot Springs, where our sample came from.

Kuroyu Hot Springs, where our sample came from.

Some years back, the lab received a sample from a colleague, R. Thane Papke, then at Montana State University, Bozeman, taken from Kuroyu Hot Springs, in Akita, Japan. Meaning "Black Onsen" in Japanese, this hot spring turns eggshells black when cooked in its 82º C, sulfur-rich acid water. 

A YS media plate growing the unknown species (upper left), next to other known Sulfolobales. Note the "fuzzy" undefined edges.

A YS media plate growing the unknown species (upper left), next to other known Sulfolobales. Note the "fuzzy" undefined edges.

Recently, the sample was taken out of storage to screen for Saccharolobus, but when uncharacteristic colonies with fuzzy edges kept popping up in the cultures, it was thought to be some kind of fungal contaminant. The implications of discovering a hyperthermophilic fungus were exciting, so we looked into these strange "contaminants". When observed under a microscope however, instead of seeing the expected fungal hyphae, what we saw were very Saccharolobus-like cells! Images from the EM confirmed that the strangely fuzzy colonies formed were actually caused by cells that were hyperflagellated.

While most Sulfolobales typically have one or a few archaellum (the archaeal flagellum), to encounter a species with so many is unique. Sequencing of the 16S ribosomal gene returned an almost identical match for both Sulfolobus tokodaii (now Sulfurisphera tokodaii) as well as Sulfurisphaera ohwakuensis, however, new sequencing data has confirmed that this is a new and uncharacterized species. Our working name for this organism is Sulfurisphaera mobilis, which describes it as a particularly motile species.

The first and best image of the hyperflagellated  S. mobilis

The first and best image of the hyperflagellated S. mobilis

 

Currently, our lab is working towards methods for culturing these cells with consistency. They seem to grow best in microaerophilic conditions, and are much less aerotolerant than S. solfataricus or other Sulfolobales we have worked with. Being able to culture more cells is the first step towards getting clearer imaging done on the cell structure and learning more about it's archaella (the archaeal flagellum). We are also troubleshooting the assembly of it's genome, which, when complete, should shed more light on it's taxonomic place within the Sulfolobales.

 

Researchers

Here's who is studying this in our lab:

Anh Le-Cook, B.S.
James Musser, Undergraduate

Key Papers

There are no papers on S. mobilis yet, but we hope to publish these results in the near future.