1. Methanogenesis: Methanogenic Euryarchaeota are well-known for their ability to produce methane (CH4) as a byproduct of their metabolism. They use simple organic compounds or carbon dioxide (CO2) and hydrogen (H2) as substrates for methanogenesis. Examples include Methanosarcina and Methanobacterium.
2. Methylotrophy: Methylotrophic Euryarchaeota can utilize methane (CH4) or other methylated compounds as their primary carbon and energy source. They convert methane into methanol, formaldehyde, and other intermediates for further metabolic reactions. Examples include Methylobacter and Methanococcoides.
3. Acetogenesis: Acetogenic Euryarchaeota produce acetate (CH3COO-) from a variety of substrates, including CO2 and H2, or by fermenting organic compounds. They play important roles in the cycling of carbon and energy within anaerobic environments. Examples include Acetobacterium and Moorella.
4. Sulfur Metabolism: Some Euryarchaeota are involved in sulfur metabolism. They can reduce sulfate (SO42-) to sulfide (HS-) or elemental sulfur (S), and use these compounds as electron donors for energy conservation. Examples include Archaeoglobus and Thermoproteus.
5. Fermentation: Euryarchaeota can also ferment organic compounds, such as sugars, amino acids, and lipids, to produce various end products like methane, carbon dioxide, and organic acids. Examples include Ferroplasma and Thermoplasma.
6. Phototrophy: A few Euryarchaeota species are phototrophic, meaning they can utilize light energy for photosynthesis. One well-known example is Halobacterium, which uses bacteriorhodopsin to capture light energy and produce ATP.
7. Thermophilic and Extreme Environments: Euryarchaeota are known for their adaptability to extreme environments. Many Euryarchaeota are thermophiles, thriving in high-temperature environments like hydrothermal vents and hot springs. Some are halophiles, adapted to highly saline environments. They can utilize unique substrates available in these extreme habitats.