Roseobacter denitrificans

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A Microbial Biorealm page on the genus Roseobacter denitrificans

Classification

Higher order taxa

Bacteria, Proteobacteria, Alphaproteobacteria, Rhodobacterales, Rhodobacteraceae, Roseobacter

Species

Roseobacter denitrificans sp. OCh114 (previously called Erythrobacter sp. OCh114)

NCBI: Taxonomy Genome

Description and significance

Roseobacter denitrificans is a purple aerobic anyoxygenic phototrophic (AAP) bacterium that dwells free-living in lakes and ocean surface waters, soils and even near deep sea hydrothermal vents. It was isolated from the surfaces of green seaweeds of the coastal marine sediments in Australia. Members of the Roseobacter clade are widespread and abundant in such marine environments, having diverse metabolisms. The purple proteobacteria in particular, are the only known organisms to capture light energy to enhance growth requiring the presence of oxygen yet do not produce oxygen themselves. The highly adaptive AAPs compose more than 10% of the microbial community in some euphotic upper ocean waters and are potentially major contributors to the fixation of the greenhouse gas CO2. The marine AAP species R. denitrificans grows not only photoheterotrophically in the presence of oxygen and light but also anaerobically in the dark using nitrate or trimethylamine N-oxide as an electron acceptor. It is the most studied AAP for this reason and is one of the main model organisms to study aerobic phototrophic bacteria.


The importances of the bacterium's genome sequence are for the following reasons: 1) The evolutionary genesis of photosynthesis genes-it is a marine bacterium, and so may be representative of the globally huge population of aerobic phototrophic bacteria and could help narrow their true evolutionary position by whole genome comparisons; 2) Pathways of carbon dioxide fixation and production-to understand the processes for its autotrophic CO2 production and the key genes involved in CO2 fixation pathways. As the only aerobic phototrophic bacterium capable of anaerobic growth with use of nitrate as a terminal electron acceptor, it can also be used to facilitate subsequent studies of the effects of oxygen on photosynthetic and other metabolic processes; 3) Light and oxygen signal transuction in gene expression the work on respiratory and photosynthetic electron transfer pathways in this organism has established this species as the model aerobic phototrophic bacterium

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Genome structure

The genome sequence of Roseobacter denitrificans was completed in 2006 by a team in Arizona State University.

The genome lacks genes that code for known photosynthetic carbon fixation pathways, with most notably missing the genes for Calvin cycle enzymes ribulose bisphosphate carboxylase (RuBisCO) and phosphoribukolkinase.

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?


Circular representation of the Roseobacter denitrificans OCh 114 chromosome.

Cell structure and metabolism

Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.

Ecology

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

There are no known pathological effects of this bacterium on humans.

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

References

[Sample reference]

1) Fleischman D and Kramer D (1998) Photosynthetic rhizobia. Biochim Biophys Acta 1364: 17-36.

2) Swingley W.D., Sadekar S., Mastrian S.D., Matthies H.J., Hao J., Ramos H., Acharya C.R., Conrad A.L., Taylor H.L., Dejesa L.C., Shah M.K., O'Huallachain M.E., Lince M.T., Blankenship R.E., Beatty J.T., Touchman J.W. ; "The complete genome sequence of Roseobacter denitrificans reveals a mixotrophic rather than photosynthetic metabolism"; J. Bacteriol. 189:683-690 (2007)

3) Candela, M., E. Zaccherini, and D. Zannoni. 2001. Respiratory electron transport and light-induced energy transduction in membranes from the aerobic photosynthetic bacterium Roseobacter denitrificans. Arch. Microbiol. 175:168-177

4) Yurkov, V. V., and J. T. Beatty. 1998. Aerobic anoxygenic phototrophic bacteria. Microbiol. Mol. Biol. Rev. 62:695-724

5) Kolber, Z. S., F. G. Plumley, A. S. Lang, J. T. Beatty, R. E. Blankenship, C. L. VanDover, C. Vetriani, M. Koblizek, C. Rathgeber, and P. G. Falkowski. 2001. Contribution of aerobic photoheterotrophic bacteria to the carbon cycle in the ocean. Science 292:2492-2495

6) Schwarze C, Carluccio AV, Venturoli G & Labahn A (2000) Photo-induced cyclic electron transfer involving cytochrome bc1 complex and reaction center in the obligate aerobic phototroph Roseobacter denitrificans. Eur J Biochem 267: 422–433

7) Yao Zhang & Nianzhi Jiao. (2007) Dynamics of aerobic anoxygenic phototrophic bacteria in the East China Sea. FEMS Microbiology Ecology 61:3, 459–469

http://www.roseobase.org/roseo/och114.html

http://genomes.tgen.org/rhodobacter.html

Arizona State University

Edited by student of Rachel Larsen