Chromatiaceae

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Chromatiaceae
Systematics
Domain : Bacteria (bacteria)
Department : Proteobacteria
Class : Gammaproteobacteria
Order : Chromatiales
Family : Chromatiaceae
Scientific name
Chromatiaceae
Bavendamm , 1924

The Chromatiaceae are a family of bacteria within the Proteobacteria . Like the Ectothiorhodospiraceae , they belong to the order Chromatiales , together they form the physiological group of the sulfur purple bacteria . They operate anoxic photosynthesis with the oxidation of hydrogen sulfide to sulfur or sulfate . In doing so, they deposit the elemental sulfur, which is formed as an end product or as an intermediate product of hydrogen sulfide oxidation, in the form of spheres or granules within the cell. The mostly anaerobic members of this family are found primarily in bodies of water , both fresh and salt water. Many species of this family used to belong to the former Thiorhodaceae.

features

The cells of most species are immobile and spherical, rods (e.g. Thiobaca ) and spirilla (e.g. Thiorhodovibrio ) also occur. Some species form gas vesicles, e.g. B. Lamprocystis roseopersicina , L. roseopersicina , Thiocapsa rosea and Thiolamprovum pedioforme . The gas vesicles serve to reach the optimal water layers, flagella are not necessary in this case. Most flagellated species therefore have no gas vesicles, one of the exceptions is Lamprocystis roseopersicina . The forms movable by flagella include u. a. Chromatium , Allochromatium , Thermochromatium and Thiocystis .

Anoxygenic photosynthesis

The purple sulfur bacteria generally use sulfide ions (S 2− ) or hydrogen sulfide (H 2 S) as electron donors for the reduction of CO 2 . They differ from phototrophs that use water (H 2 O) as an electron donor, such as cyanobacteria and plants , and which therefore form elementary oxygen (O 2 ) as the oxidation product of water (oxygenic photosynthesis). In the photosynthesis of purple sulfur bacteria, however, no oxygen is released, their photosynthesis is therefore anoxygenic.

The Chromatiaceae oxidize sulphides or hydrogen sulphide to elemental sulfur and deposit the sulfur in the form of globules within the cell (intracellularly). The sulfur can then be further oxidized to sulfate. This course corresponds to the sulfur oxidation of the Ectothiorhodospiraceae, only that they deposit the sulfur extracellularly. A species of the Ectothiorhodospiraceae, Thiorhodospira sibirica , not only deposits the sulfur extracellularly, but also in the periplasmic space of the cell.

With autotrophic growth and when carbon dioxide (CO 2 ) is used as the only carbon source , cell material is built up with the assimilation of CO 2 using the Calvin cycle . Chromatiaceae can also usually use simple organic compounds, so CO 2 is not the only source of carbon, as is the case with plants. Acetate and pyruvate are the most widely used organic carbon sources. Polysaccharides , poly-β-hydroxybutyrate and polyphosphates are often formed as energy or phosphate reserves and stored in the cells. The elemental sulfur deposited in the cell acts as an electron donor and energy reserve; in the absence of hydrogen sulfide, the stored sulfur is further oxidized to sulfate.

Chlorophyll is usually the bacteriochlorophyll α. Some species also have Bacteriochlorophyll β, examples of which are: Thiococcus pfennigii , Thioalkalicoccus sibiricus and Thioflavicoccus mobilis . The carotenoids that occur in this family belong to the groups of Spirilloxanthine ( Thermochromatium , Thiocapsa and some types of Allochromatium ), Rhodopinale ( Allochromatium ) and Okenones (e.g. Chromatium ). Tetrahydrospirilloxanthine also occurs ( Thiococcus pfennigii ).

Together with the sulfur-free purple bacteria, the so-called green sulfur bacteria and the green non-sulfur bacteria (Chloroflexi), the sulfur purple bacteria belong to the anoxygenic phototrophic bacteria. The well-known phototrophic cyanobacteria, on the other hand, are characterized by the formation of oxygen: Since water serves as an electron donor, oxygen is released. They are therefore oxygen phototrophic.

Other metabolic pathways

Regarding the metabolism, one can distinguish between two lines within the Chromatiaceae, the flexible and the specialized (i.e. inflexible) species. Physiologically rather inflexible species are, for example, Chromatium okenii , Chromatium weissei , Allochromatium warmingii , Isochromatium buderi , Thiospirillum jenense and Thiococcus pfennigii . Without available sulfide there is no growth, sulfide is the only usable electron donor, hydrogen cannot be used as an electron donor. Despite the ability to use acetate and pyruvate, they remain dependent on carbon dioxide.

The physiologically diverse species include Thiocystis violacea , Allochromatium vinosum , Thiocapsa roseopersicina and Lamprobacter modestohalophilus . Some of them are able to grow without reduced sulfur compounds. For example, Allochromatium vinosum can use hydrogen as an electron donor. Some can use organic compounds as electron donors. Also thiosulphate and iron (II) ions can act as electron donors.

The majority of the Chromatiaceae are also nitrogen fixers : They reduce elemental nitrogen (N 2 ) to ammonia and thus count among the diazotrophic bacteria.

Systematics

The following genera belong to the Chromatiaceae family:

See also

swell

  1. Irina Bryantseva, Vladimir M. Gorlenko, Elena I. Kompantseva, Johannes F. Imhoff, Jörg Suling and Lubov 'Mityushina: Thiorhodospira sibirica gen. Nov., Sp. nov., a new alkaliphilic purple sulfur bacterium from a Siberian soda lake. In: International Journal of Systematic Bacteriology . Vol. 49, 1999, pp. 697-703 PMID 10319493
  2. ^ Armin Ehrenreich and Friedrich Widdel: Anaerobic oxidation of ferrous iron by purple bacteria, a new type of phototrophic metabolism. In: Applied and Environmental Microbiology . Vol. 60, 1994, pp. 4517-4526
  3. JP Euzéby: List of Prokaryotic names with Standing in Nomenclature - Chromatiaceae ( Memento of the original from March 2, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (As of December 23, 2014) @1@ 2Template: Webachiv / IABot / www.bacterio.cict.fr

literature

  • Hans Mattern: About a red color in the Lower Lake Constance due to the sulfur bacterium Chromatium , in: Writings of the Association for the History of Lake Constance and its Surroundings , 93rd year 1975, pp. 159–166 ( digitized version )
  • Michael T. Madigan, John M. Martinko, Jack Parker: Brock - Microbiology . 11th edition. Pearson Studium, Munich 2006, ISBN 3-8274-0566-1
  • Johannes Imhoff: The Chromatiaceae In: Martin Dworkin, Stanley Falkow, Eugene Rosenberg, Karl-Heinz Schleifer, Erko Stackebrandt (Eds.) The Prokaryotes, A Handbook of the Biology of Bacteria . 7 volumes, 3rd edition, Springer-Verlag, New York et al. O., 2006, ISBN 0-387-30740-0 . Vol. 6: Proteobacteria: Gamma Subclass ISBN 0-387-30746-X ;