Aquificae

Aquificae

Aquificae is a phylum of bacteria that are known for their ability to thrive in extreme environments, particularly in hot springs and hydrothermal vents. These bacteria are thermophilic, meaning they can survive and grow at high temperatures, often above 70°C (158°F). Aquificae are considered one of the deepest branches of the bacterial domain, providing insights into early life on Earth.

Characteristics

Aquificae are Gram-negative bacteria, characterized by their rod-shaped morphology. They are chemolithoautotrophs, meaning they obtain energy by oxidizing inorganic substances, such as hydrogen, and fix carbon dioxide to synthesize organic compounds. This metabolic capability allows them to inhabit environments that are rich in inorganic compounds but low in organic nutrients.

Metabolism

Aquificae primarily utilize the reverse tricarboxylic acid cycle for carbon fixation, a process that is considered ancient and efficient under high-temperature conditions. They are capable of oxidizing hydrogen, sulfur, and thiosulfate, using oxygen or nitrate as electron acceptors.

Habitat

Members of the Aquificae phylum are typically found in extreme environments such as:

• Hot springs
• Hydrothermal vents
• Volcanic soils

These environments are characterized by high temperatures, often exceeding 70°C, and can also be acidic or alkaline.

Taxonomy

The phylum Aquificae includes several genera, with Aquifex being one of the most studied. Other notable genera include Thermocrinis and Hydrogenobacter.

Genera

• Aquifex - Known for its ability to oxidize hydrogen and sulfur compounds.
• Thermocrinis - Typically found in neutral to alkaline hot springs.
• Hydrogenobacter - Found in both terrestrial and marine hydrothermal systems.

Evolutionary Significance

Aquificae are considered to be among the most ancient lineages of bacteria, providing valuable insights into the evolution of life on Earth. Their ability to thrive in extreme conditions similar to those of early Earth makes them a subject of interest in studies of abiogenesis and the potential for life on other planets.

Research and Applications

Research on Aquificae has implications for understanding the limits of life and the potential for biotechnological applications. Their enzymes, stable at high temperatures, are of interest for industrial processes that require robust catalysts.

See Also

• Thermophile
• Extreme environment
• Chemolithoautotroph

External Links

• NCBI Taxonomy Browser: Aquificae