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Chlorobium
 
 
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Chlorobium (also known as Chlorochromatium) is a genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
 of green sulfur bacteria
Green sulfur bacteria

The green sulfur bacteria are a family of obligately anaerobic organism photoautotrophic bacterium. Most closely related to the nonetheless distant Bacteroidetes, they are accordingly assigned their own phylum....
. They are photolithotrophic oxidizers of sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
 and most notably utilise a noncyclic electron transport chain to reduce NAD+. Hydrogen sulfide
Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the chemical formula Hydrogen2Sulfur. This colorless, toxic and flammable gas is partially responsible for the foul odor of egg and flatulence....
 is used as an electron source and carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 its carbon source.

Chlorobium species
Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
 exhibit a dark green color; in a Winogradsky column
Winogradsky column

The Winogradsky Column is a simple device for culturing a large diversity of microorganisms. Invented by Sergei Winogradsky, the device is a column of pond mud and water mixed with a carbon source such as newspaper or egg-shells and a sulfur source such as gypsum or egg-yolk....
, the green layer often observed is composed of Chlorobium. This genus lives in strictly anaerobic conditions below the surface of a body of water, commonly the anaerobic
Anaerobic organism

An anaerobic organism is any organism that does not require oxygen for growth and may even die in its presence....
 zone of a eutrophic lake
Eutrophic lake

A eutrophic lake is a lake with high primary productivity, the result of high nutrient content. These lakes are subject to excessive algal blooms, resulting in poor water quality....
.

Chlorobium aggregatum is a species which exists in a symbiotic relationship with a colorless, nonphotosynthetic bacteria.






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Encyclopedia


Chlorobium (also known as Chlorochromatium) is a genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
 of green sulfur bacteria
Green sulfur bacteria

The green sulfur bacteria are a family of obligately anaerobic organism photoautotrophic bacterium. Most closely related to the nonetheless distant Bacteroidetes, they are accordingly assigned their own phylum....
. They are photolithotrophic oxidizers of sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
 and most notably utilise a noncyclic electron transport chain to reduce NAD+. Hydrogen sulfide
Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the chemical formula Hydrogen2Sulfur. This colorless, toxic and flammable gas is partially responsible for the foul odor of egg and flatulence....
 is used as an electron source and carbon dioxide
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
 its carbon source.

Chlorobium species
Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring....
 exhibit a dark green color; in a Winogradsky column
Winogradsky column

The Winogradsky Column is a simple device for culturing a large diversity of microorganisms. Invented by Sergei Winogradsky, the device is a column of pond mud and water mixed with a carbon source such as newspaper or egg-shells and a sulfur source such as gypsum or egg-yolk....
, the green layer often observed is composed of Chlorobium. This genus lives in strictly anaerobic conditions below the surface of a body of water, commonly the anaerobic
Anaerobic organism

An anaerobic organism is any organism that does not require oxygen for growth and may even die in its presence....
 zone of a eutrophic lake
Eutrophic lake

A eutrophic lake is a lake with high primary productivity, the result of high nutrient content. These lakes are subject to excessive algal blooms, resulting in poor water quality....
.

Chlorobium aggregatum is a species which exists in a symbiotic relationship with a colorless, nonphotosynthetic bacteria. This species looks like a bundle of green bacteria, attached to a central rod-like cell which can move around with a flagellum
Flagellum

A flagellum is a tail-like structure that projects from the cell body of certain prokaryotic and eukaryotic cells, and it functions in locomotion....
. The green, outer bacteria use light to oxidize sulfide
Sulfide

The term sulfide refers to several types of chemical compounds containing sulfur in its lowest oxidation number of −2.Formally, "sulfide" is the dianion, S2−, which exists in strongly alkaline aqueous solutions formed from H2S or alkali metal salts such as Li2S, Na2S, and K2...
 into sulfate
Sulfate

In inorganic chemistry, a sulfate is a salt of sulfuric acid....
. The inner cell, which is not able to perform photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
, reduces the sulfate into sulfide. These bacteria divide in unison, giving the structure a multicellular appearance which is highly unusual in bacteria.

Chlorobium species are thought to have played an important part in mass extinction events on Earth. If the oceans turn anoxic (due to the shutdown of ocean circulation) then chlorobium would be able to out compete other photosynthetic life. They would produce huge quantites of methane
Methane

Methane is a chemical compound with the molecular formula . It is the simplest alkane, and the principal component of natural gas. Methane's bond angles are 109.5 degrees....
 and hydrogen sulphide which would cause global warming
Global warming

Global warming is the increase in the Instrumental temperature record of the Earth's near-surface air and the oceans since the mid-twentieth century and its projected continuation....
 and acid rain
Acid rain

Acid rain is rain or any other form of Precipitation that is unusually acidic. It has harmful effects on plants, aquatic animals, and infrastructure....
. This would have huge consequences for other oceanic organisms and also for terresterial organisms. Evidence for abundant chlorobium populations is provided by chemical fossils found in sediments deposited at the cretaceous mass extinction.

The complete C. tepidum genome
Genome

In classical genetics, the genome of a diploid organism including eukarya refers to a full set of chromosomes or genes in a gamete; thereby, a regular somatic cell contains two full sets of genomes....
, which consists of 2.15 megabases (Mb), was sequenced and published in 2002. It synthesizes chlorophyll
Chlorophyll

Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Its name is derived from Greek language: ?????? and f????? ....
 a and bacteriochlorophyll
Bacteriochlorophyll

Bacteriochlorophylls are photosynthetic pigments that occur in various phototrophic bacterium. They are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria....
s (BChls) a and c, of which the model organism
Model organism

A model organism is a species that is extensively studied to understand particular biology phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms....
 has been used to ellucidate the biosynthesis of BChl c. Several of its carotenoid
Carotenoid

Carotenoids are organic compound pigments that are naturally occurring in chromoplasts of plants and some other photosynthesis organisms like algae, some types of fungus and some bacterium....
 metabolic pathway
Metabolic pathway

In biochemistry, a metabolic pathway is a series of chemistry reactions occurring within a cell . In each pathway, a principal chemical is modified by chemical reactions....
s (including a novel lycopene
Lycopene

Lycopene is a bright red carotenoid pigment and phytochemical found in tomatoes and other red fruits.In plants, algae, and other Photosynthesis, lycopene is an important intermediate in the biosynthesis of many carotenoids, including beta carotene, responsible for yellow, orange or red pigmentation, photosynthesis, and photo-protection....
 cyclase
Cyclase

A cyclase is an enzyme, almost always a lyase, that catalysis a chemical reaction to form a cyclic compound. Important cyclase enzymes include:...
) have similar counterparts in cyanobacteria
Cyanobacteria

Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis....
.