(redirected from chemosynthetic)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.


process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source, rather than the sunlight used for energy in photosynthesisphotosynthesis
, process in which green plants, algae, and cyanobacteria utilize the energy of sunlight to manufacture carbohydrates from carbon dioxide and water in the presence of chlorophyll. Some of the plants that lack chlorophyll, e.g.
..... Click the link for more information.
. Most life on earth is fueled directly or indirectly by sunlight. There are, however, certain groups of bacteria, referred to as chemosynthetic autotrophs, that are fueled not by the sun but by the oxidation of simple inorganic chemicals, such as sulfates or ammonia. Chemosynthetic autotrophs are a necessary part of the nitrogen cyclenitrogen cycle,
the continuous flow of nitrogen through the biosphere by the processes of nitrogen fixation, ammonification (decay), nitrification, and denitrification. Nitrogen is vital to all living matter, both plant and animal; it is an essential constituent of amino acids,
..... Click the link for more information.
. Some groups of these bacteria are well suited to conditions that would have existed on the earth billions of years ago, leading some to postulate that these are living representatives of the earliest life on earth. This view has been supported by the discovery of small ecosystems that thrive in the hot (350°C;/660°F;) water found around hydrothermal vents on the ocean floor. In these ecosystems, the primary producers in the food web are bacteria whose life functions are fueled by inorganic chemicals that seep up from the earth's crust. See also autotrophautotroph
, in biology, an organism capable of synthesizing its own organic substances from inorganic compounds. Autotrophs produce their own sugars, lipids, and amino acids using carbon dioxide as a source of carbon, and ammonia or nitrates as a source of nitrogen.
..... Click the link for more information.



a type of nutrition characteristic of certain bacteria whose only carbon source is CO2 obtained from the energy of oxidation of inorganic compounds.

The discovery of chemosynthesis by S. N. Vinogradskii in 1887 significantly altered prevailing views on the main types of metabolism in living organisms. Unlike photosynthesis, chemosynthesis does not involve the use of light energy but energy derived from oxidation-reductions that must be adequate for the synthesis of adenosine triphosphate (ATP) and that must exceed 10 kcal/mole. Chemosynthetic bacteria are not strictly a taxonomic group; they are classified according to the inorganic substrate they oxidize. They include microorganisms that oxidize hydrogen, carbon monoxide, reduced sulfur compounds, iron, ammonia, nitrites, and antimony.

Hydrogen bacteria are the most numerous and varied group of chemosynthetic organisms. They perform the reaction 6H2 + 2O2 + CO2 = (CH2O) + 5H2O, in which (CH2O) is the conventional designation of the organic substances formed. Compared with other autotrophic microorganisms, hydrogen bacteria have a high growth rate and may produce a large biomass; they are also able to grow on mediums containing organic matter, that is, they are mixotrophic or facultatively chemoautotrophic.

Carboxydation bacteria are similar to hydrogen bacteria, but they oxidize CO by the reaction 25CO + 12O2 + H2O + 24CO2+ (CH2O). Sulfur bacteria oxidize hydrogen sulfide, thiosulfate, and molecular sulfur to sulfuric acid. Some, for example, Thiobacillus ferrooxidans, oxidize sulfide minerals and ferrous oxide. The capacity of various aquatic sulfur bacteria for chemosynthesis has not yet been demonstrated. Nitrifying bacteria oxidize ammonia to nitrite (first stage of nitrification) and nitrite to nitrate (second stage). Chemosynthesis occurs under anaerobic conditions in some denitrifying bacteria, which oxidize hydrogen or sulfur but often require organic matter for biosynthesis. Chemosynthesis has been described in some strictly anaerobic meth-anogenic bacteria according to the reaction 4H2 + CO2 = CH4 + 2H2O.

The biosynthesis of organic compounds in chemosynthesis is achieved by autotrophic assimilation of CO2 (Calvin carbon reduction cycle) just as in photosynthesis. Energy is obtained in the form of ATP from electron transfer via the chain of respiratory enzymes incorporated into the bacterial cell membrane. Some oxidized substances give off electrons to the chain at the cytochrome c level, thereby creating additional energy to synthesize the reducing agent. Owing to the fairly large consumption of energy, chemosynthetic bacteria—with the exception of hydrogen bacteria—produce a small biomass but oxidize a substantial amount of inorganic matter. Since chemosynthetic bacteria control the oxidative parts of the cycle of major elements in the biosphere, they are vitally important in biogeochemistry. Hydrogen bacteria can be used to obtain protein and to free the atmosphere from CO2 in closed ecological systems. Chemosynthetic bacteria are highly varied morphologically. Although most of them are pseudomonades, they are also found among budding and filamentous bacteria, spirilla, leptospira, and corynebacteria.


Kuznetsov, S. I. Mikroflora ozer i ee geokhimicheskaia deiatel’nost’. Leningrad, 1970.
Zavarzin, G. A. Litotrofnye mikroorganizmy. Moscow, 1972.
Karavaiko, G. I., S. I. Kuznetsov, and A. I. Golomzik. Rol’ mikroorganizmov v vyshelachivanii metallov iz rud. Moscow, 1972.



The synthesis of organic compounds from carbon dioxide by microorganisms using energy derived from chemical reactions.
References in periodicals archive ?
Alvin discovers "Lost City" in the Atlantic, a previously unknown environment where seawater reacts with mantle rock to produce unusual kinds geological structures and chemosynthetic communities.
In this context, it must be noted that not only plant mono-extracts or extract combinations are able to exhibit synergy effects, but also single natural products or extracts in combinations with chemosynthetics or antibiotics.
In view of advantages with the low impurity content, costs and so on of chemosynthetic method, compared to gene recombination method and animal and plant extraction method, it rapidly develops.
Title: Research Report on Chinese Chemosynthetic Polypeptide Drug Industry, 2012 Published: July, 2012 Pages: 60 Price: US$ 3,000 http://marketpublishers.
Chemosynthetic Ecosystem Study Literature Review and Data Synthesis, Volume II.
What is the current sulfide source at the Catalina Basin skeleton, and why does the chemosynthetic assemblage hug the bones?
Here, sulfide may become limiting for the two snail species living at the top of the zone, but not for the mussels, whose symbionts may be able to take up and use thiosulfate directly as a chemosynthetic source instead of, or as well as, free sulfide.
Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites.
Woods Hole Oceanographic Institution biologist Tim Shank calls the vent sites "Earth's largest chemosynthetic community," where inhabitants live without sunlight and instead convert chemicals from vent fluids into energy and nutrient sources.
13]C value of free-living chemosynthetic bacteria at GC234 was estimated to be between -40 and -24[per thousand] (see subsection below) and photosynthetic primary production in the Gulf of Mexico has a value of approximately -19[per thousand] (Fry 1984).
We had not anticipated the presence of these chemosynthetic bacteria in the tissues of Riftia pachyptila, clams, and mussels.
childressi or other chemosynthetic material may be underor over-estimated if the local carbon isotope signature is not specifically known.