Chemosynthesis
Life-sustaining process that converts inorganic compounds into organic matter.
Chemosynthesis is the biological conversion of one or more carbon-containing molecules and nutrients into organic matter using the oxidation of inorganic compounds or ferrous ions as a source of energy, rather than sunlight. It is a fundamental process that supports life in dark environments, such as deep-sea hydrothermal vents, and is carried out by phylogenetically diverse chemoautotrophs, including sulfur-oxidizing Gammaproteobacteria, Campylobacterota, Aquificota, methanogenic archaea, and neutrophilic iron-oxidizing bacteria. Chemosynthesis is significant because it enables biomass production where photosynthesis is impossible and may have been the first type of metabolism to evolve on Earth.
In the deep ocean, where sunlight does not penetrate, many microorganisms use chemosynthesis to create organic matter from single-carbon molecules. In rare locations where molecular hydrogen is present, the reaction between carbon dioxide and hydrogen can yield methane and provide substantial energy for biomass production. More commonly, energy is derived from oxidizing substances like hydrogen sulfide or ammonia, with or without oxygen. For instance, giant tube worms host symbiotic bacteria in a specialized organ that fix carbon dioxide using hydrogen sulfide as an energy source, producing sugars and amino acids while releasing solid sulfur globules rather than oxygen. These chemosynthetic communities support large animal populations at hydrothermal vents, cold seeps, methane clathrates, whale falls, and isolated cave water. The concept was first proposed in 1890 by Sergei Winogradsky, who suggested microbes could live solely on inorganic matter. Wilhelm Pfeffer later coined the term "chemosynthesis" in 1897. This hypothesis was confirmed nearly ninety years later with the 1977 discovery of hydrothermal vents at the Galapagos Rift, where tube worms were found to rely on chemosynthetic bacteria oxidizing sulfides. In 2013, researchers discovered bacteria living in oceanic crust rock, subsisting on hydrogen produced by chemical reactions between seawater and olivine, and synthesizing methane from hydrogen and carbon dioxide. Chemosynthesis remains an active research area, particularly regarding nitrifying bacteria and the transformation of elements in biogeochemical cycles.
- field
- Biochemistry, Microbiology
- known_for
- Biological conversion of carbon molecules into organic matter using inorganic energy sources
Lore & Background
Chemosynthesis is the biological conversion of carbon-containing molecules, typically carbon dioxide or methane, and nutrients into organic matter using energy derived from oxidizing inorganic compounds such as hydrogen gas, hydrogen sulfide, or ferrous ions, rather than sunlight. Organisms that perform this process, called chemoautotrophs, are phylogenetically diverse and include sulfur-oxidizing Gammaproteobacteria, Campylobacterota, Aquificota, methanogenic archaea, and neutrophilic iron-oxidizing bacteria. In dark ocean regions, many microorganisms use chemosynthesis to produce biomass from single-carbon molecules. Where hydrogen gas is available, the reaction between carbon dioxide and hydrogen can produce methane, providing sufficient energy for biomass production. More commonly, energy comes from oxidizing substances like hydrogen sulfide or ammonia, with or without oxygen. Chemosynthetic microorganisms are consumed by other organisms, and symbiotic associations with heterotrophs are common, supporting large animal populations at hydrothermal vents, methane clathrates, cold seeps, whale falls, and isolated cave water. In hydrogen sulfide chemosynthesis, as seen in giant tube worms, carbon dioxide is fixed using hydrogen sulfide as an energy source, producing carbohydrates and solid sulfur globules instead of oxygen. This process was first proposed by Sergei Winogradsky in 1890, who suggested some microbes could live solely on inorganic matter. Wilhelm Pfeffer coined the term "chemosynthesis" in 1897 for energy production by oxidation of inorganic substances with autotrophic carbon dioxide assimilation. The discovery was confirmed in the 1970s when hydrothermal vents were found at the Galapagos Rift, and Colleen Cavanaugh later verified that chemosynthetic bacteria oxidizing sulfides allowed tube worms to thrive there. In 2013, bacteria were discovered living in oceanic crust rock, subsisting on hydrogen produced by chemical reduction of olivine by seawater, synthesizing methane from hydrogen and carbon dioxide.
Reader's Guide
Chemosynthesis is a cornerstone of biogeochemical cycles, enabling the transformation of chemical elements in environments devoid of sunlight. Colleen Cavanaugh then proposed and confirmed that chemosynthetic bacteria oxidizing sulfides allow tube worms to thrive near vents. The process supports large animal populations at hydrothermal vents, methane clathrates, cold seeps, whale falls, and isolated cave water. It has been hypothesized to support life below the surface of Mars and Jupiter's moon Europa, and may represent the earliest metabolism on Earth. Ongoing research focuses on nitrifying bacteria, thermophilic sulfate-reducing bacteria like Thermodesulfovibrio yellowstonii, and the potential of chemosynthetics to accumulate valuable resources for human needs.
Did You Know?
- Hydrogen sulfide chemosynthesis produces solid globules of sulfur, visible as yellow globules in the cytoplasm of bacteria like purple sulfur bacteria.
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