Rhodospirillum rubrum
A Microbial Biorealm page on the genus Rhodospirillum rubrum
Classification
Higher order taxa
Bacteria; Proteobacteria; Alphaproteobacteria; Rhodospirillales; Rhodospirillaceae; Rhodospirillum;
Species
Rhodospirillum rubrum
Description and significance
Found in mud, pond water, & sewage
DOES NOT infect humans or animals
Mesophile, optimum temperature 25-30 C Gram-negative, mostly unsaturated, some saturated fats in cell wall
Has multilayered outer envelops
Complex pigments call “Carotenoid” and “BacteriocholophyII” are found in relatively large particles called “Chromatophores” which gives the bacteria it’s distinctive color. Electron microscopy revel that the “Chromatophore” are flatten disk Purple colored under anaerobic conditions, Colorless in aerobic
Carotenoids give purple-red color
they help in light absorption for photosynthesis
Found in invaginations of the cytoplasmic membrane
Polarly Flagellated Spiralla Length 3-10 um, Width 0.8-1.0 um Facultative anaerobe
Can use alcoholic fermentation or aerobic respiration
Photosynthesis is active under anaerobic conditions, but is genetically suppressed in the presence of O2
O2 is not a byproduct of photosynthesis, sulfur is
Can grow autotrophically or heterotrophically when phototrophic
Oxidizes carbon monoxide
Can use sulfide (AT LOW CONCENTRATIONS) as an electron donor in CO2 reduction
Contains no chlorophyll a (absorption spectra 430-662)
contains chlorphyll b (absorption spectra 660-680 nm) and bacteriochlorophylls (800-925 nm)
advantageous to use more energy of electromagnetic spectra
Nitrogen fixing bacteria
Converts atmospheric nitrogen gas to ammonia
N2 --(nitrogenase)--> NH4+
Biotech uses
Consumption
Source of animal food and agricultural fertilizer
Biological plastic production from precursors of poly-hydroxy-butric-acid
Biological hydrogen fuel (evolution of nitrogenase)
Vitamin production
Academia
Model system of light to chemical energy conversion and for nitrogen fixation pathways
Subject of radiation resistance studies
Cell free systems including photosynthesis and ATP synthesis
Genome structure
Finished Circular chromosome 4,352,825 base pairs 65% GC Plasmid 53,732 bp 60% GC Total 3,850 protein coding genes 83 RNA genes
Gene breakdown 6.9% Transcription 4.6% Translation, ribosome structure, biosynthesis 4.0% Replication, recombination and repair 7.9% Signal transduction mechanisms 5.9% Cell wall, membrane biogenesis 6.6% energy production and conversion 5.0% Carbohydrate transport and metabolism 9.9% Amino acid transport and metabolism 4.7% Coenzyme transport and metabolism 3.7% Lipid transport and metabolism 6.5% Inorganic ion transport and metabolism
Cell structure and metabolism
Interesting features of cell structure; how it gains energy; what important molecules it produces.
Basic Metabolism Versatile organism that can obtain energy through alternative mechanism.
Ex. Rhodospirillum can grow in dark chemo-tropical environment with the presence of O2 or they can grow in a photo-tropical environment without O2.
Phototrophically grown Rhodospirillum contain photosynthetic electron transport and ATP synthesis enzymes in their membrane and contain a membrane bound pyrophosphatase. Chemotrophically dark grown Rhodospirillum contain low concentration of bacteriochlorophyII and carotenoids and has no bound pyrophosphatase in their membrane.
Ecology
Habitat; symbiosis; contributions to the environment.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Current Research
Some journal articles I found interesting.
1. Evidence that Ubiquinone Is a Required Intermediate for Rhodoquinone Biosynthesis in Rhodospirillum rubrum http://jb.asm.org/cgi/content/abstract/192/2/436
2. Effect of Perturbation of ATP Level on the Activity and Regulation of Nitrogenase in Rhodospirillum rubrum http://jb.asm.org/cgi/content/abstract/191/17/5526
3. Modes of hydrogen production in the photosynthetic bacterium, Rhodospirillum rubrum
- Renewable energy
http://gradworks.umi.com/33/83/3383605.html
Cool Factor
Describe something you find "cool" about this microbe.
Possible topics:
Photosynthetic, but does not have light harvesting complex 2 (LHC2), which is commonly found in many photosynthetic bacteria.
References
Edited by student of Iris Keren
