47-449: The green sulfur bacteria are a phylum , Chlorobiota , of obligately anaerobic photoautotrophic bacteria that metabolize sulfur. Green sulfur bacteria are nonmotile (except Chloroherpeton thalassium , which may glide) and capable of anoxygenic photosynthesis . They live in anaerobic aquatic environments. In contrast to plants, green sulfur bacteria mainly use sulfide ions as electron donors. They are autotrophs that utilize
94-439: A reduction potential of around +300 mV. While this is not positive enough to strip electrons from water to synthesize O 2 ( E 0 = +820 mV), it can accept electrons from other sources like H 2 S , thiosulphate or Fe ions. This transport of electrons from donors like H 2 S to the acceptor Fd is called linear electron flow or linear electron transport. The oxidation of sulfide ions leads to
141-567: A and c. Like other green sulfur bacteria C. tepidum requires light and specific compounds to perform anoxygenic photosynthesis . C. tepidum differs from other green sulfur bacteria in that it cannot easily use H 2 or Fe as electron donors, relying on elemental sulfur, sulfide, and thiosulfate instead. To fulfill their metabolic requirements, they reside primarily in anaerobic sulfur rich environments such as anaerobic levels of stratified lakes and lagoons, anaerobic levels of layered organic bacterial mats , and in hot springs where there
188-551: A certain degree of morphological or developmental similarity (the phenetic definition), or a group of organisms with a certain degree of evolutionary relatedness (the phylogenetic definition). Attempting to define a level of the Linnean hierarchy without referring to (evolutionary) relatedness is unsatisfactory, but a phenetic definition is useful when addressing questions of a morphological nature—such as how successful different body plans were. The most important objective measure in
235-407: A character unique to a sub-set of the crown group. Furthermore, organisms in the stem group of a phylum can possess the "body plan" of the phylum without all the characteristics necessary to fall within it. This weakens the idea that each of the phyla represents a distinct body plan. A classification using this definition may be strongly affected by the chance survival of rare groups, which can make
282-402: A group ("a self-contained unity"): "perhaps such a real and completely self-contained unity is the aggregate of all species which have gradually evolved from one and the same common original form, as, for example, all vertebrates. We name this aggregate [a] Stamm [i.e., stock] ( Phylon )." In plant taxonomy , August W. Eichler (1883) classified plants into five groups named divisions,
329-596: A group containing Viridiplantae and the algal Rhodophyta and Glaucophyta divisions. The definition and classification of plants at the division level also varies from source to source, and has changed progressively in recent years. Thus some sources place horsetails in division Arthrophyta and ferns in division Monilophyta, while others place them both in Monilophyta, as shown below. The division Pinophyta may be used for all gymnosperms (i.e. including cycads, ginkgos and gnetophytes), or for conifers alone as below. Since
376-400: A phylum based on body plan has been proposed by paleontologists Graham Budd and Sören Jensen (as Haeckel had done a century earlier). The definition was posited because extinct organisms are hardest to classify: they can be offshoots that diverged from a phylum's line before the characters that define the modern phylum were all acquired. By Budd and Jensen's definition, a phylum is defined by
423-471: A phylum much more diverse than it would be otherwise. Total numbers are estimates; figures from different authors vary wildly, not least because some are based on described species, some on extrapolations to numbers of undescribed species. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million. The kingdom Plantae
470-689: A phylum, other phylum-level ranks appear, such as the case of Bacillariophyta (diatoms) within Ochrophyta . These differences became irrelevant after the adoption of a cladistic approach by the ISP, where taxonomic ranks are excluded from the classifications after being considered superfluous and unstable. Many authors prefer this usage, which lead to the Chromista-Protozoa scheme becoming obsolete. Currently there are 40 bacterial phyla (not including " Cyanobacteria ") that have been validly published according to
517-401: A set of characters shared by all its living representatives. This approach brings some small problems—for instance, ancestral characters common to most members of a phylum may have been lost by some members. Also, this definition is based on an arbitrary point of time: the present. However, as it is character based, it is easy to apply to the fossil record. A greater problem is that it relies on
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#1732851213841564-401: A subjective decision about which groups of organisms should be considered as phyla. The approach is useful because it makes it easy to classify extinct organisms as " stem groups " to the phyla with which they bear the most resemblance, based only on the taxonomically important similarities. However, proving that a fossil belongs to the crown group of a phylum is difficult, as it must display
611-424: A term that remains in use today for groups of plants, algae and fungi. The definitions of zoological phyla have changed from their origins in the six Linnaean classes and the four embranchements of Georges Cuvier . Informally, phyla can be thought of as groupings of organisms based on general specialization of body plan . At its most basic, a phylum can be defined in two ways: as a group of organisms with
658-438: Is Bacteriochlorophylls c or d in green species and e in brown species, and is located in the chlorosomes and plasma membranes. Chlorosomes are a unique feature that allow them to capture light in low-light conditions. The majority of green sulfur bacteria are mesophilic , preferring moderate temperatures, and all live in aquatic environments. They require anaerobic conditions and reduced sulfur; they are usually found in
705-467: Is a paraphyletic taxon, which is less acceptable to present-day biologists than in the past. Proposals have been made to divide it among several new kingdoms, such as Protozoa and Chromista in the Cavalier-Smith system . Protist taxonomy has long been unstable, with different approaches and definitions resulting in many competing classification schemes. Many of the phyla listed below are used by
752-505: Is a different, more effective mechanism. However, most green sulfur bacteria contain a homolog of the SQR gene. The oxidation of thiosulfate to sulfate could be catalyzed by the enzymes in the SO x system. Phylum In biology , a phylum ( / ˈ f aɪ l əm / ; pl. : phyla ) is a level of classification or taxonomic rank below kingdom and above class . Traditionally, in botany
799-510: Is abundant sulfur. C. tepidum and other green sulfur bacteria also play a large role within the carbon and sulfur cycles . Within the sulfur cycle, they contribute to the oxidative branch by oxidizing reduced sulfur compounds. Within anaerobic sediment layers C. tepidum is able to couple carbon and sulfur cycling in a metabolically favorable way. As it was mentioned before, C. tepidum performs anoxygenic photosynthesis. Within each cell there are 200–250 chlorosomes that are attached to
846-405: Is defined in various ways by different biologists (see Current definitions of Plantae ). All definitions include the living embryophytes (land plants), to which may be added the two green algae divisions, Chlorophyta and Charophyta , to form the clade Viridiplantae . The table below follows the influential (though contentious) Cavalier-Smith system in equating "Plantae" with Archaeplastida ,
893-804: Is difficult to distinguish these properties and therefore the taxonomic division is sometimes unclear. Generally, Chlorobium are rod or vibroid shaped and some species contain gas vesicles. They can develop as single or aggregate cells. They can be green or dark brown. The green strains use photosynthetic pigments Bchl c or d with chlorobactene carotenoids and the brown strains use photosynthetic pigment Bchl e with isorenieratene carotenoids. Low amounts of salt are required for growth. Prosthecochlori s are made up of vibroid, ovid or rod shaped cells. They start as single cells that form appendages that do not branch, referred to as non-branching prosthecae. They can also form gas vesicles. The photosynthetic pigments present include Bchl c, d or e. Furthermore, salt
940-472: Is generally included in kingdom Fungi, though its exact relations remain uncertain, and it is considered a protozoan by the International Society of Protistologists (see Protista , below). Molecular analysis of Zygomycota has found it to be polyphyletic (its members do not share an immediate ancestor), which is considered undesirable by many biologists. Accordingly, there is a proposal to abolish
987-537: Is necessary for growth. Chlorobaculum develop as single cells and are generally vibroid or rod-shaped. Some of these can form gas vesicles. The photosynthetic pigments in this genus are Bchl c, d or e . Some species require NaCl (sodium chloride) for growth. Members of this genus used to be a part of the genus Chlorobium, but have formed a separate lineage. The genus Chloroherpeton is unique because members of this genus are motile. They are flexing long rods, and can move by gliding. They are green in color and contain
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#17328512138411034-460: Is physically located between the chlorosomes and the P840 RC. The FMO complex helps efficiently transfer the energy absorbed by the antena to the reaction center. PSI and Type I reaction centers are able to reduce ferredoxin (Fd), a strong reductant that can be used to fix CO 2 and reduce NAD . Once the reaction center (RC) has given an electron to Fd it becomes an oxidizing agent (P840) with
1081-422: Is usually sulfur, which is deposited outside of the cell, and the end product is sulfate. The sulfur, which is deposited extracellularly, is in the form of sulfur globules, which can be later oxidized completely. The mechanisms of sulfur oxidation in green sulfur bacteria are not well characterized. Some enzymes thought to be involved in sulfide oxidation include flavocytochrome c, sulfide:quinone oxidoreductase and
1128-710: The Bacteriological Code Currently there are 2 phyla that have been validly published according to the Bacteriological Code Other phyla that have been proposed, but not validly named, include: Chlorobaculum tepidum Chlorobium tepidum Wahlund et al. 1996 Chlorobaculum tepidum , previously known as Chlorobium tepidum , is an anaerobic, thermophilic green sulfur bacteria first isolated from New Zealand. Its cells are gram-negative and non- motile rods of variable length. They contain chlorosomes and bacteriochlorophyll
1175-552: The Catalogue of Life , and correspond to the Protozoa-Chromista scheme, with updates from the latest (2022) publication by Cavalier-Smith . Other phyla are used commonly by other authors, and are adapted from the system used by the International Society of Protistologists (ISP). Some of the descriptions are based on the 2019 revision of eukaryotes by the ISP. The number of protist phyla varies greatly from one classification to
1222-527: The SO x system. Flavocytochrome can catalyze the transfer of electrons to cytochromes from sulfide, and these cytochromes could then move the electrons to the photosynthetic reaction center. However, not all green sulfur bacteria produce this enzyme, demonstrating that it is not needed for the oxidation of sulfide. Sulfide:quinone oxidoreductase (SQR) also helps with electron transport, but, when alone, has been found to produce decreased rates of sulfide oxidation in green sulfur bacteria, suggesting that there
1269-403: The cytoplasmic side of reaction centers inserted within the inner cell membrane . The ellipsoidal shaped complexes act as light harvesting antenna to capture energy. Within each chlorosome are 215,000 ± 80,000 bacteriochlorophyll C that act as pigment molecules and absorb unique wavelengths of light relative to their color. C. tepidum contains genes that play an important role in
1316-415: The reverse tricarboxcylic acid cycle . C. tepidum contains a genome that contains 2.15 Mbp, within there are a total of 2,337 genes (of these genes, there are 2,245 protein coding genes and 56 tRNA and rRNA coding genes). It's synthesis of chlorophyll a and bacteriochlorophylls a and c make it a model organism used to elucidate the biosynthesis of bacteriochlorophylls c . Present in
1363-473: The reverse tricarboxylic acid cycle to perform carbon fixation . They are also mixotrophs and reduce nitrogen. Green sulfur bacteria are gram-negative rod or spherical shaped bacteria. Some types of green sulfur bacteria have gas vacuoles that allow for movement. They are photolithoautotrophs, and use light energy and reduced sulfur compounds as the electron source. Electron donors include H 2 , H 2 S, S. The major photosynthetic pigment in these bacteria
1410-503: The P840 reaction center can transfer the electrons to menaquinone (MQ: MQH 2 ) which returns the electrons to the P840 via an electron transport chain (ETC). On the way back to the RC the electrons from MQH2 pass through a cytochrome bc 1 complex (similar to the complex III of mitochondria) that pumps H ions across the membrane. The electrochemical potential of the protons across
1457-491: The Zygomycota phylum. Its members would be divided between phylum Glomeromycota and four new subphyla incertae sedis (of uncertain placement): Entomophthoromycotina , Kickxellomycotina , Mucoromycotina , and Zoopagomycotina . Kingdom Protista (or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all eukaryotes that are not plants, animals, or fungi. Protista
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1504-458: The above definitions is the "certain degree" that defines how different organisms need to be members of different phyla. The minimal requirement is that all organisms in a phylum should be clearly more closely related to one another than to any other group. Even this is problematic because the requirement depends on knowledge of organisms' relationships: as more data become available, particularly from molecular studies, we are better able to determine
1551-555: The bacteria need very little energy for cellular maintenance. A species of green sulfur bacteria has been found living near a black smoker off the coast of Mexico at a depth of 2,500 m in the Pacific Ocean . At this depth, the bacterium, designated GSB1, lives off the dim glow of the thermal vent since no sunlight can penetrate to that depth. Green sulfur bacteria has also been found living on coral reef colonies in Taiwan, they make up
1598-504: The first publication of the APG system in 1998, which proposed a classification of angiosperms up to the level of orders , many sources have preferred to treat ranks higher than orders as informal clades. Where formal ranks have been provided, the traditional divisions listed below have been reduced to a very much lower level, e.g. subclasses . Wolf plants Hepatophyta Liver plants Coniferophyta Cone-bearing plant Phylum Microsporidia
1645-484: The flow of electrons. In green sulfur bacteria the reaction center is associated with a large antena complex called the chlorosome that captures and funnels light energy to the reaction center. The chlorosomes have a peak absorption in the far red region of the spectrum between 720 and 750 nm because they contain bacteriochlorophyll c, d and e. A protein complex called the Fenna-Matthews-Olson complex (FMO)
1692-429: The genome of C. tepidum are a multitude of genes that protect the bacterium against the presence of oxygen. The fact that such a large part of the genome is used to encode for protections against oxygen points to the possibility that C. tepidum spent a long period of its evolutionary history in proximity to oxygen, and therefore needed pathways that ensured that living in the presence of oxygen would not substantially harm
1739-2091: The majority of a "green layer" on these colonies. They likely play a role in the coral system, and there could be a symbiotic relationship between the bacteria and the coral host. The coral could provide an anaerobic environment and a source of carbon for the bacteria. The bacteria can provide nutrients and detoxify the coral by oxidizing sulfide. One type of green sulfur bacteria, Chlorobaculum tepidum , has been found in sulfur springs. These organisms are thermophilic , unlike most other green sulfur bacteria. Chloroherpeton thalassium Prosthecochloris aestuarii P. marina P. vibrioformis Chlorobaculum tepidum C. thiosulfatiphilum " Chlorobaculum chlorovibrioides " Chlorobaculum parvum C. luteolum C. limicola C. phaeovibrioides C. clathratiforme . phaeobacteroides Chloroherpeton thalassium Gibson et al. 1985 " Ca. Thermochlorobacter aerophilum " Liu et al. 2012b P. marina Bryantseva et al. 2020 P. vibrioformis (Pelsh 1936) Imhoff 2003 P. aestuarii Gorlenko 1970 (type sp.) P. ethylica Shaposhnikov, Kondrateva & Federov 1959 ex Kyndt, Van Beeumen & Meyer 2020 C. parvum Imhoff 2003 C. tepidum (Wahlund et al. 1996) Imhoff 2003 (type sp.) C. limnaeum Imhoff 2003 C. thiosulfatiphilum Imhoff 2022 C. limicola Nadson 1906 emend. Imhoff 2003 (type sp.) C. phaeobacteroides Pfennig 1968 C. luteolum (Schmidle 1901) emend. Imhoff 2003 C. phaeovibrioides Pfennig 1968 " C. chlorochromatii " Meschner 1957 ex Vogl et al. 2006 C. clathratiforme (Szafer 1911) Imhoff 2003 " C. ferrooxidans " Heising et al. 1998 " Ca. C. masyuteum" Lambrecht et al. 2021 Green sulfur bacteria are family Chlorobiaceae. There are four genera; Chloroherpeton , Prosthecochloris , Chlorobium and Chlorobaculum . Characteristics used to distinguish between these genera include some metabolic properties, pigments, cell morphology and absorption spectra. However, it
1786-501: The membrane is used to synthesize ATP by the F o F 1 ATP synthase . This cyclic electron transport is responsible for converting light energy into cellular energy in the form of ATP. Green sulfur bacteria oxidize inorganic sulfur compounds to use as electron donors for anaerobic photosynthesis, specifically in carbon dioxide fixation. They usually prefer to utilize sulfide over other sulfur compounds as an electron donor, however they can utilize thiosulfate or H 2 . The intermediate
1833-540: The methylation of the C-8 and C-12 carbons of bacteriochlorophyll C. This methylation allows for BChl C levels to fluctuate in response to a change in the availability of light, resulting in a high efficiency of light harvesting and allowing C. tepidum to survive in areas of very low light intensity. Light energy is harvested by the chlorosomes and used in conjunction with H 2 , reduced sulfur compounds, or ferrous iron to preform redox reactions and provide energy to fix CO 2 via
1880-411: The next. The Catalogue of Life includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista. In addition, less popular classification schemes unite Ochrophyta and Pseudofungi under one phylum, Gyrista , and all alveolates except ciliates in one phylum Myzozoa , later lowered in rank and included in a paraphyletic phylum Miozoa . Even within
1927-528: The other hand, the highly parasitic phylum Mesozoa was divided into two phyla ( Orthonectida and Rhombozoa ) when it was discovered the Orthonectida are probably deuterostomes and the Rhombozoa protostomes . This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of placing taxa in clades without any formal ranking of group size. A definition of
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1974-434: The photosynthetic pigment Bchl c as well as γ-carotene . Salt is required for growth. The green sulfur bacteria use a Type I reaction center for photosynthesis. Type I reaction centers are the bacterial homologue of photosystem I (PSI) in plants and cyanobacteria . The GSB reaction centers contain bacteriochlorophyll a and are known as P840 reaction centers due to the excitation wavelength of 840 nm that powers
2021-449: The production of sulfur as a waste product that accumulates as globules on the extracellular side of the membrane. These globules of sulfur give green sulfur bacteria their name. When sulfide is depleted, the sulfur globules are consumed and further oxidized to sulfate. However, the pathway of sulfur oxidation is not well-understood. Instead of passing the electrons onto Fd, the Fe-S clusters in
2068-478: The relationships among phyla within larger clades like Ecdysozoa and Embryophyta . The term phylum was coined in 1866 by Ernst Haeckel from the Greek phylon ( φῦλον , "race, stock"), related to phyle ( φυλή , "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as
2115-469: The relationships between groups. So phyla can be merged or split if it becomes apparent that they are related to one another or not. For example, the bearded worms were described as a new phylum (the Pogonophora) in the middle of the 20th century, but molecular work almost half a century later found them to be a group of annelids , so the phyla were merged (the bearded worms are now an annelid family ). On
2162-466: The term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts the terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering
2209-420: The top millimeters of sediment. They are capable of photosynthesis in low light conditions. The Black Sea , an extremely anoxic environment, was found to house a large population of green sulfur bacteria at about 100 m depth. Due to the lack of light available in this region of the sea, most bacteria were photosynthetically inactive. The photosynthetic activity detected in the sulfide chemocline suggests that
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