Phototrophic Anoxygenic Bacteria

Cross Index	Phototrophic Anoxygenic Bacteria
SuperSet	Prokaryote, Eubacteria,
Compare
Contrast	Oxygenic Phototrophic Bacteria Archaea
Subset	Purple Bacteria Internal sulfur granules Amoebobacter, Chromatium, Lamprobacter modestohalophilus, Lamprocystis roseopersicina, Thiocapsa, Thiocystis, Thiodicyton, Thiopedia rosea , Thiospirillum jenense, External sulfur granules Ectothiorhodospira no granules Rhodobacter, Rhodocyclus, Rhodomicrobium vannieli, Rhodopila globiformis, Rhodopseudomonas, Rhodospirillum, Green Bacteria Sulfur granules Anachloris perfilievii, Chlorobium, Chloroherpeton thalassium, Pelodictyon, Prosthecachloris no sulfur granules Heliobacillus mobilis , Heliobacterium chlorum Multicellular filamentous Chloroflexus aurantiacus, Chloronema, Heliothrix oregonensis, Oscillochloris Anaerobic chemotropic Erythrobacter longus,

Morphology

Anoxygenic Phototrophic Bacteria

CELLULAR

Staining	Gram-negative
Morphology	Cells are spherical or ovoid or are of short or long rods or spirals of various width;
Motility	are motile by polar, subpolar or peritrichous flagella or are nonmotile
Specialized structures	None of the described species contains gas vacuoles. Internal photosynthetic membranes are continuous with the cytoplasmic membrane and consist of fingerlike intrusions, vesicles or lamellae polysaccharides, poly-B-hydroxybutyric acid and polyphosphate have been found

Division

and divide by binary fission or show polar growth and budding

COLONIAL

Solid surface

Liquid

Colour of cell suspensions is green, yellowish-green, yellowish-brown, brown, brown-red, red or purple-violet.

Growth Parameters

Anoxygenic Phototrophic Bacteria

PHYSIOLOGICAL

Tropism	Under anaerobic conditions in the light, all species grow as photoheterotrophs with various organic substrates or as photoautotrophs with either molecular hydrogen or, in some species, sulfide, thiosulfate or elemental sulfur as electron donor and CO2 as sole carbon source (growth factors are required in most cases). Under microaerobic to aerobic conditions in the dark, many representatives can grow as chemoheterotrophs, and some grow as chemoautotrophs.
Oxygen	In most species, the formation of pigments and of the internal membrane systems are repressed under aerobic conditions but become derepressed at oxygen tensions below a certain level. Some species may metabolize anaerobically in the dark with sugars and either nitrate, DMSO or trimethylamine-N-oxide as electron sink or, though poorly, with metabolic intermediates as electron acceptors. Some representatives are very sensitive to oxygen; others grow equally well under aerobic conditions in the dark at the full oxygen tension of air and under anaerobic conditions in the light.
pH
Temperature
Requirements	One or more vitamins are generally required as growth factors; most commonly required are biotin, thiamine, niacin and p-aminobenzoic acid. These compounds are rarely needed by species of the Chromatiaceae and Ectothiorhodospiraceae, which may require vitamin B12 as sole growth factor. Growth of most species is enhanced by small amounts of yeast extract, and some species have a complex nutrient requirement. Ammonia, dinitrogen and several organic nitrogen compounds are generally used as nitrogen source, nitrate is also used by some strains The majority of the species are able to assimilate sulfate as sole sulfur source; only a few species depend on the presence of reduced sulfur compounds as sulfur source. Sulfide is inhibitory for many species already at low concentrations; some, however, exhibit a remarkable tolerance towards this compound
Products
Enzymes
Unique features	Photosynthetic pigments are located in the cytoplasmic membrane and the internal membrane systems and are bacteriochlorophyll a or b (esterified with phytol or geranylgeraniol) and various types of carotenoids..

ENVIRONMENTAL

Habitat	Members of this group are widely distributed in nature and found not only in fresh-water, marine and hypersaline environments but also in moist soils and paddy fields. They live preferably in aquatic habitats with significant amounts of soluble organic matter and low oxygen tension, but they rarely form coloured blooms, which are characteristically formed by representative of other families of anoxygenic phototrophic bacteria
Lifestyle
Pathogenicity

Distribution

Genome

Anoxygenic Phototrophic Bacteria

G+C Mol %

52.0-73.2 (Bd and Tm).

Reference

Anoxygenic Phototrophic Bacteria

The Prokaryotes	p
Bergey's Systematatic	p
Bergey's Determinative	p 353-376

References