Thermophilic Bacteria

Small ridges of rock filled with water
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

Cyanobacteria Calothrix
pH & Temperature: pH6–9, 30–45°C (86–113°F)
Color: dark brown mats
Metabolism: photosynthesis by day; fermentation by night
Location: Mammoth Hot Springs, Upper, Midway, and Lower geyser basins

Phormidium
pH & Temperature: pH 6–8, 35–57°C (95–135°F)
Color: orange mats
Metabolism: photosynthesis
Location: Mammoth Hot Springs, Upper, Midway, and Lower geyser basins

Oscillatoria
pH & Temperature: pH 6–8, 36–45°C (96–113°F)
Color: orange mats
Metabolism: photosynthesis; oscillating moves it closer to light sources.
Location: Mammoth Hot Springs, Chocolate Pots

Synechococcus
pH & Temperature: pH 7–9, 52–74°C (126–165°F)
Color: green mats Metabolism: photosynthesis by day; fermentation by night
Location: Mammoth Hot Springs Upper, Midway, and Lower geyser basins

Green Sulfur Chlorobium
pH & Temperature: pH 6–9, 32–52°C (90–126°F)
Color: dense, dark green mats
Metabolism: anaerobic photosynthesis—produces sulfate and sulfur, not oxygen.
Location: Mammoth Hot springs, Calcite Springs

Green non-sulfur Chloroflexus
pH & Temperature: pH 7–9, 35–85°C (95–185°F)
Color: green mats
Metabolism: anaerobic photosynthesis
Location: Mammoth Hot Springs, Upper, Midway, and Lower geyser basins

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

Deinococcus-Thermus Thermus
pH & Temperature: pH 5–9, 40–79°C (104–174°F)
Color: bright red or orange streamers; contains carotenoid pigments that act as sunscreen.
Location: Lower Geyser Basin

 

Last updated: August 9, 2017

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