Cross Index Rhodocyclus
SuperSet Prokaryote, Eubacteria Anoxygenic Phototrophic Bacteria
Compare Purple Bacteria

Green Bacteria

Anaerobic chemotropic Erythrobacter longus,

Contrast Oxygenic Phototrophic Bacteria Archaea


Morphology Rhodocyclus
Staining Gram-negative
Morphology Cells are ovoid or rod-shaped, 0.3-0.7 um in diameter, and., may produce capsules and slime, and may form chains of cells..
Motility Rhodocyclus pupureus is non motile Rhodocylcus tennuis and Rhodocyclus gelatinosus have polar flagella
Specialized structures Internal photosynthetic membranes are present as vesicles
Division binary fission
Solid surface  
Liquid Rhodocyclus gelatinosus produces a large amount of slime during active growth which causes semdimentation of the cells into a gelatinous layer


Growth Parameters Rhodocyclus
Tropism Photoautotrophic growth is possible in the presence of molecular hydrogen as an electron donor

Growth occurs photo-heterotrophically under anaerobic conditions in the light with a variety of organic compounds as carbon and electron sources. Most species perform an oxidative metabolism and grow as chemoheterotrophs at the full oxygen tension of air in the dark.

Oxygen growth preferably under anaerobic conditions in the light but Rhodocyclus can grow microaerobically or aerobically in the dark
pH pH 5.2- 7.5 optimum pH 6.0
Temperature optimum 30 o C
Requirements Rhodocyclus purpureus requires vitamin B12
Products Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spheroidene series
Unique features  


Genome Rhodocyclus
G+C Mol % 64.8-72.4 (Bd)


Reference Rhodocyclus
First citation Pfennig, N.1978. Rhodocyclus purpureus gen. nov. and sp. nov., a ring-shpaed, vitamin B12 requiring member of the family Rhodospirillaceae IJSB 28: 283-288
The Prokaryotes  
Bergey's Systematatic p 1678 J. F. Imhoff and H. G. Truper
Bergey's Determinative p 358