Thermophilic Bacteria

Almost every hot spring or geyser in Yellowstone hosts bacteria. The travertine terraces in Mammoth Hot Springs host thermophilic bacteria.

NPS

 

The word “bacteria” is often associated with disease, but only a few kinds of bacteria cause problems for humans. The other thousands of bacteria, although all simple organisms, play a complex role in Earth’s ecosystems. In fact, cyanobacteria made our oxygen-rich atmosphere possible. They were the first photosynthesizers, more than 3 billion years ago. Without bacteria, we would not be here.

Almost any hot spring or geyser you see hosts bacteria. Some chemosynthesize, changing hydrogen or sulfur into forms other thermophiles can use. Most photosynthesize, providing oxygen to other thermophiles. All of the cyanobacteria and green nonsulfur bacteria photosynthesize. Some fulfill both roles. For example, Thermus sp.—which are photosynthetic—also may be able to oxidize arsenic into a less toxic form.

Individual bacteria may be rod or sphere shaped, but they often join end to end to form long strands called filaments. These strands help bind thermophilic mats, forming a vast community or mini-ecosystem. Other groups of bacteria form layered structures resembling tiny towers, which can trap sand and other organic materials.

 

Thermophilic Bacteria in Yellowstone National Park

Cyanobacteria

Name	pH	Temperature	Color	Metabolism	Location
Calothrix	6–9	30–45°C (86–113°F)	Dark brown mats	Photosynthesis by day; fermentation by night	Mammoth Hot Springs; Upper, Midway, and Lower geyser basins
Phormidium	6–8	35–57°C (95–135°F)	Orange mats	Photosynthesis	Mammoth Hot Springs; Upper, Midway, and Lower geyser basins
Oscillatoria	6–8	36–45°C (96–113°F)	Orange mats	Photosynthesis; oscillating moves it closer to light sources.	Mammoth Hot Springs, Chocolate Pots
Synechococcus	7–9	52–74°C (126–165°F)	Green mats	Photosynthesis by day; fermentation by night	Mammoth Hot Springs; Upper, Midway, and Lower geyser basins

 

Green Sulfur

Name	pH	Temperature	Color	Metabolism	Location
Chlorobium	6–9	32–52°C (90–126°F)	Dense, dark green mats	Anaerobic photosynthesis—produces sulfate and sulfur, not oxygen	Mammoth Hot Springs, Calcite Springs

 

Green non-sulfur

Name	pH	Temperature	Color	Metabolism	Location
Chloroflexus	7–9	35–85°C (95–185°F)	Green mats	Anaerobic photosynthesis	Mammoth Hot Springs; Upper, Midway, and Lower geyser basins

 

Aquifex

Name	pH	Temperature	Color	Metabolism	Location
Hydrogenobaculum	3–5.5	55–72°C (131–162°F)	Yellow and white streamers	Uses hydrogen, hydrogen sulfide and carbon dioxide as energy sources; can use arsenic in place of hydrogen sulfide	Norris Geyser Basin, Amphitheater Springs

 

Deinococcus-Thermus

Name	pH	Temperature	Color	Note	Location
Thermus	5–9	40–79°C (104–174°F)	Bright red or orange streamers	Contains carotenoid pigments that act as sunscreen	Lower Geyser Basin