Summary
Bacteria at hydrothermal vents fix carbon using energy from inorganic chemical reactions.
In depth
Hydrogen sulfide oxidation powers carbon fixation at hydrothermal vents, supporting tube worms, clams and mussels with symbionts. Discovered in 1977 near the Galapagos.
Chemosynthetic bacteria oxidise reduced compounds (H2S, NH3, Fe2+) for ATP and fix CO2. They are primary producers in the dark.
Example: nitrifying bacteria in soils are chemosynthetic.
Chemosynthetic organisms make organic molecules using energy from the oxidation of inorganic compounds instead of light. Examples include sulfur-oxidising bacteria (hydrogen sulfide), nitrifying bacteria (ammonia or nitrite), iron-oxidising bacteria, hydrogen-oxidising bacteria and methanotrophs.
The energy is used to fix CO2 via the Calvin cycle or other pathways. At hydrothermal vents and cold seeps, chemosynthetic bacteria form the base of food webs, often living symbiotically in tube worms and clams. On land, nitrifiers are key to the nitrogen cycle.
Example: Thiobacillus oxidises sulfur in soil and produces sulfuric acid.
Frequently asked questions
What is Chemosynthesis?
Bacteria at hydrothermal vents fix carbon using energy from inorganic chemical reactions.
Which area of biology covers Chemosynthesis, and how advanced is it?
Chemosynthesis is one of the 53 topics in Metabolism & Bioenergetics. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Anaerobic Respiration in Prokaryotes, Cellular Respiration, Anabolism and Catabolism.
Why does Chemosynthesis matter?
It shows that life can be independent of sunlight and informs the search for life on other planets and moons.
Can you give an example of Chemosynthesis?
Some life may exist without sunlight.
What should I learn before Chemosynthesis?
Work through the Beginner topics in Metabolism & Bioenergetics first, such as Metabolism, Anabolism and Catabolism, ATP, then return to Chemosynthesis. Advanced topics assume the Intermediate vocabulary.
What topics are related to Chemosynthesis?
The closest topics to Chemosynthesis are Anaerobic Respiration in Prokaryotes, Cellular Respiration, Anabolism and Catabolism, Glycolysis. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Chemosynthesis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Chemosynthesis. To practise the whole of Metabolism & Bioenergetics, use the Metabolism & Bioenergetics quiz.
How is Chemosynthesis different from Anaerobic Respiration in Prokaryotes?
Chemosynthesis: Bacteria at hydrothermal vents fix carbon using energy from inorganic chemical reactions. Anaerobic Respiration in Prokaryotes: Bacteria use alternative terminal acceptors such as nitrate or sulfate in the electron transport chain. Read both side by side and note what each one explains.
How should I study Chemosynthesis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Anaerobic Respiration in Prokaryotes and explain the difference aloud. Finally, take the Metabolism & Bioenergetics quiz and come back to this page for any question you miss.