Chromatiaceae

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 purple sulfur bacteria. Do you operate a anoxic photosynthesis with the oxidation of hydrogen sulfide to sulfur or sulfate. They store the elementary sulfur which is produced as a final product or as an intermediate product of the oxidation of hydrogen sulphide, as in the form of beads or granules within said cell. The most anaerobic members of this family are found mainly in waters both fresh and in salt water. Previously, many species of this family were asked to former Thiorhodaceae.

Features

The cells of most types are stationary and spherical, and rods (eg Thiobaca ) and spirilla (eg Thiorhodovibrio ) before coming. Some species produce gas vesicles, eg Lamprocystis roseopersicina, L. roseopersicina, Thiocapsa rosea and Thiolamprovum pedioforme. The gas vesicles are used to achieve the optimum water layers, flagella are not necessary in this case. Most flagellated species thus have no gas vesicles, one of the exceptions is Lamprocystis roseopersicina. The movable by flagella forms include, inter alia, Chromatium, Allochromatium, Thermochromatium and Thiocystis.

The anoxygenic photosynthesis

Sulfur purple bacteria generally employ sulfide ions (S2 - ), and hydrogen sulfide ( H2S) as an electron donor for the reduction of CO2. They therefore differ from phototrophs that use water ( H2O) as an electron donor, such as cyanobacteria and plants, and therefore elemental as the oxidation product of the water oxygen (O2 ) form ( oxygenic photosynthesis ). During photosynthesis, the purple sulfur bacteria, however, no oxygen is released, photosynthesis is thus anoxygen.

Chromatiaceae oxidize the sulphides or hydrogen sulphide to elemental sulfur and storing the sulfur in the form of beads within the cell (intracellular ) from. The sulfur may then be further oxidised to sulphate. This course corresponds to the sulfur oxidation of Ectothiorhodospiraceae, only the effect of depositing the sulfur extracellularly. A type of Ectothiorhodospiraceae, Thiorhodospira sibirica superimposed sulfur but not only extracellularly but also in the periplasmic space of the cell.

In autotrophem growth and if as a sole carbon source of carbon dioxide ( CO2) is used, the structure of cellular material under assimilation of CO2 is done using the Calvin cycle. Chromatiaceae can also use simple organic compounds, as a rule, that is, CO2 is not the only source of carbon, as is the case with the plants. Acetate and pyruvate are the most commonly used organic carbon sources. Polysaccharides, poly - β -hydroxybutyrate and polyphosphates are often formed as an energy or phosphate reserves and stored in the cells. The deposited in the cell elemental sulfur acts as an electron donor and an 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 possess bacteriochlorophyll β, examples are: Thiococcus pfennigii, Thioalkalicoccus sibiricus and Thioflavicoccus mobilis. The carotenoids that are found in this family, are among the groups of Spirilloxanthine ( Thermochromatium, Thiocapsa and some types of Allochromatium ) Rhodopinale ( Allochromatium ) and Okenone (eg Chromatium ). Also Tetrahydrospirilloxanthin occurs ( Thiococcus pfennigii ).

Together with the non-sulfur purple bacteria, the so-called green sulfur bacteria and the green non- sulfur bacteria ( Chloroflexi ) include the purple sulfur bacteria to anoxygen phototrophic bacteria. The known phototrophic cyanobacteria, however, are characterized by the formation of oxygen: Since water is used as an electron donor oxygen is released. They are thus oxygen phototroph.

Other metabolic pathways

Concerning the metabolism, one can distinguish between two lines within the Chromatiaceae, flexible and specialized (ie inflexible ) species. Physiologically rather inflexible types include Chromatium okenii, Chromatium weissei, Allochromatium warmingii, Isochromatium buderi, Thiospirillum Jenense and Thiococcus pfennigii. Without available sulfide is no growth, the only usable electron sulfide, hydrogen can not be used as the electron donor. Despite the ability to use and acetate and pyruvate, they remain dependent on carbon dioxide.

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

The majority of Chromatiaceae are also nitrogen fixers: they reduce elemental nitrogen (N2 ) to ammonia and are therefore among the diazotrophic bacteria.

System

The following genera belong to the family Chromatiaceae:

• Allochromatium Imhoff et al. 1998
• Chromatium Winogradsky 1888
• Halochromatium Imhoff et al. 1998
• Isochromatium Imhoff et al. 1998
• Lamprobacter Gorlenko et al. 1988
• Marichromatium Imhoff et al. 1998
• Nitrosococcus Winogradsky 1892
• Phaeochromatium Shivali et al. 2012
• Rhabdochromatium ( Winogradsky 1888) Dilling et al. 1996
• Rheinheimera Brettar et al. 2002
• Thermochromatium Imhoff et al. 1998
• Thioalkalicoccus Bryantseva et al. 2000
• Thiobaca Rees et al. 2002
• Thiocapsa Winogradsky 1888
• Thiococcus Imhoff et al. 1998
• Thiocystis Winogradsky 1888
• Thiodictyon Winogradsky 1888
• Thioflavicoccus Imhoff and Pfennig 2001
• Thiohalocapsa Imhoff et al. 1998
• Thiolamprovum Guyoneaud et al. 1998
• Thiopedia Winogradsky 1888
• Anil Kumar Thiophaeococcus et al. 2008
• Thiorhodococcus Guyoneaud et al. 1998
• Thiorhodovibrio Overmann et al. 1993
• Thiospirillum Winogradsky 1888

• Acidiferrobacter Hallberg et al. 2011
• Alkalilimnicola Yakimov et al. 2001
• Alkalispirillum Rijkenberg et al. 2002
• Aquisalimonas Márquez et al. 2007
• Arhodomonas Adkins et al. 1993
• Ectothiorhodosinus Gorlenko et al. 2004
• Ectothiorhodospira Pelsh 1936
• Halorhodospira Imhoff and Suling 1997
• Natronocella Sorokin et al. 2007
• Nitrococcus Watson and Waterbury 1971
• Thioalbus Park et al. 2011
• Thioalkalivibrio Sorokin et al. 2001
• Thiohalospira Sorokin et al. 2008
• Thiorhodospira Bryantseva et al. 1999