Ralstonia metallidurans: Difference between revisions

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==Classification==
==Classification==
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Kingdom: Bacteria
Kingdom: Bacteria
 
Phylum: Proteobacteria
Phylum: Proteobacteria
 
Class: Beta Proteobacteria
Class: Beta Proteobacteria
 
Order: Burkholderiales
Order:Burkholderiales
 
Family: Ralstoniaceae
Family: Ralstoniaceae
 
Genus: Ralstonia
Genus: Ralstonia
 
Species: R. metallidurans
Species: R. metallidurans
 
[Others may be used.  Use [http://www.ncbi.nlm.nih.gov/Taxonomy/ NCBI] link to find]
Strain: CH3


===Species===
===Species===
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''Genus species''
 
Ralstonia metallidurans
''Ralstonia basilensis ''<br/ >
''Ralstonia campinensis''<br/ >
''Ralstonia eutropha''<br/ >
''Ralstonia gilardii''<br/ >
''Ralstonia insidiosa''<br/ >
''Ralstonia mannitolilytica''<br/ >
''Ralstonia paucula''<br/ >
''Ralstonia pickettii''<br/ >
''Ralstonia respiraculi''<br/ >
''Ralstonia solanacearum''<br/ >
''Ralstonia syzygii''<br/ >
''Ralstonia taiwanensis''<br/ >
 
 
==Description and significance==
==Description and significance==
Ralstonia metallidurans is a gram-negative, non-spore forming bacillus that flourishes in millimolar concentrations of toxic heavy metals. It and other metal-resistant members of the genus Ralstonia are frequently found in sediments and soils with a high content of heavy metals from diverse geographical locations.
 
The reference strain, CH34, was first isolated in 1976 from the sludge of a zinc decantation tank in Belgium that was polluted with high concentrations of several heavy metals.
''Ralstonia metallidurans'' is a gram-negative microbe that does not form spores. It is unique in that it can fluorish in millimolar concentrations of heavy metals, such as gold, that are normally toxic to bacteria. According to discoverer Frank Reith, ''Ralstonia metallidurans'' "is able to survive in concentrations of gold that would kill most other micro-organisms" (1). Not only can these microbes withstand toxic concentrations of metals, they are found to be able to precipitate gold. Although it is unknown exactly how this process works, it is "possible that the microbe screens out gold as part of an effort to detoxify its immediate environment" (1).
Ralstonia metallidurans was identified by Frank Reith of Australian National University and his colleagues as the common denominator among bacteria comprising a dried organic biofilm found on the surface of gold grains collected from a park and gold mines in southern New South Wales and northern Queensland, Australia. Reith further isolated and grew the bacteria in the lab and found that R. metallidurans have the unique ability to precipitate gold. According to Reith, "A unique attribute of R. metallidurans is that it is able to survive in concentrations of gold that would kill most other micro-organisms." Metals like gold are normally toxic to bacteria. It is still unknown exactly how the bacteria help to precipitate the gold grains, but is possible that the microbe screens out the gold as part of an effort to detoxify its immediate environment.  
 
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.
''Ralstonia metallidurans'' and other metal resistant microbes are often found in sediments with a high content of heavy metals from diverse geographical locations. The reference strain, CH34, was first discovered in 1976, from the sludge of a zinc decantation tank in Belgium that was polluted with high concentrations of several heavy metals. Frank Reith (and colleagues) at Australian National University further isolated and grew the bacteria in the lab.
Include a picture or two (with sources) if you can find them.
 
The significance of this microbe lays in that its genome contains plasmids that confer resistance to heavy metals, such as Zinc, Mercury, Cadmium, Cobalt, etc.
In 1992, Kostman et al. developed a PCR-ribotyping method for B. cepacia which could detect significant polymorphisms in the intergenic 16S-23S spacer of rRNA genes (7). In 1997, Shreve et al. used PCR-RFLP analysis for the 16S and 23S regions of the rRNA genes in an epidemiological study of B. cepacia infection (21). Segonds et al. used PCR-RFLP analysis of the 16S rRNA gene to differentiate Burkholderia species (20).


==Genome structure==
==Genome structure==
A typical feature of these metal-resistant Ralstonia is the presence of one or two large megaplasmids which contain genes for multiple resistances to heavy metals. The reference strain, CH34, contains two large plasmids, pMOL28 (180 kb) and pMOL30 (240 kb). Together these plasmids confer resistance to Zn, Cd, Co, Pb, Cu, Hg , Ni and Cr. Both plasmids are low copy number and stably maintained even without selective pressure. They are self-transferable at low frequencies.  
The genome of ''R. metallidurans CH34'' has been extensively studied. It contains two large plasmids that encode for heavy metal resistance. pMOL28 (163 kb) furnishes tolerance to Nickel, Mercury, and Cobalt; pMOL30 (238 kb) confers resistance to Zinc, Cadmium, Mercury, and Cobalt (3). These plasmids are self-transmissible in homologous matings, but at low frequencies (3). The entire genome is approximately 6900 kb in size. In addition to the plasmids pMOL28 and pMOL30, it also contains two circular chromosomes (8). Furthermore, the genome encodes "8 P-type ATPase involved in metal efflux specialized in lead, cadmium, thallium and/or copper efflux, and several other mechanism involved in metal processing" (1). Together, these genetic elements contribute to the microbe's unique ability to survive in harsh environments.
 
The amplicons of R. paucula isolates were digested with AciI and AlwI. All of the strains shared a single pattern with each of the two endonucleases. The AciI pattern was composed of eight fragments (340, ~200, 122, 119, 92, 75, 49, and 44 bp), and the AlwI pattern was composed of four fragments (418, 218, 130, and 75 bp)
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?


==Cell structure and metabolism==
==Cell structure and metabolism==
Its optimal growth temperature is 30 çC.
''R. metallidurans'' is a gram-negative bacillus (rod shaped). Therefore, it has the structural features of gram-negative bacteria, such as cell walls containing peptidoglycan, an outer membrane containing LPS and porins, and a periplasmic space (2).


Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces.
''R. metallidurans'' is able to utilize a variety of substrates as its carbon source. It can grow autotrophically using molecular hydrogen as an energy source and carbon dioxide as its carbon source. Furthermore, in the presence of nitrate, it can grow anaerobically (6). When grown lithoautotrophically on molecular hydrogen, it forms cytoplasmic NAD-reducing and membrane bound hydrogenase. It does not grow on fructose (3) and its optimal growth temperature is 30 C (4).


==Ecology==
==Ecology==
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Due to its ability to withstand toxic metals, ''R. metallidurans'' has been studied to utilize this characteristic in areas of bioremediation (10). Furthermore, new findings of a lead binding protein isolated from ''R. metallidurans'' is key in preventing lead poisoning (11).


==Pathology==
==Pathology==
How does this organism cause disease?  Human, animal, plant hosts?  Virulence factors, as well as patient symptoms.
''R. metallidurans'' has not been found to be pathogenic to humans. However, a near relative, ''R. solancearum'', that shares some of the metal resistant genes, has been found to cause disease in plants (10).
R. paucula has been isolated from pool water, groundwater, and bottled mineral water (2, 9, 17) and from clinical specimens. Despite its low pathogenicity, it is now recognized as an opportunistic pathogen which can generate serious infections such as septicemia, peritonitis, abscess, and tenosynovitis, particularly in immunocompromised patients


==Application to Biotechnology==
==Application to Biotechnology==
Does this organism produce any useful compounds or enzymes?  What are they and how are they used?
''R. metallidurans'' has been found to produce enzymes that may be used in constructing a fuel cell (12). These enzymes are able to oxidize hydrogen, which can ultimately result in the production of electricity. Scientists are in the process of researching this phenomenom (12).
 
==Current Research==
==Current Research==


Enter summaries of the most recent research here--at least three required
Currently, ''R. metallidurans'' are being studied for their potential in fuel cell production (12). Also, as mentioned above, this microbe has the unique ability to precipitate gold. Current research is trying to better understand this interesting characteristic(1). Furthermore, ''R. metallidurans'' has been studied for its use in the prevention of lead contamination by the fluorescent signaling of its lead binding protein (11).
Recently, several authors have reported the use of PCR-ribotyping (3, 5, 7, 8, 12, 22, 23) and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis (20, 21) for strain differentiation within various bacterial species. Thus, an evaluation for the ability of these two techniques to distinguish between R. paucula strains and between strains belonging to other Ralstonia species (R. eutropha, R. pickettii, R. gilardii, and R. solanacearum) is going on. As the ribosomal DNA (rDNA) intergenic spacer can contain genes coding for tRNA (15, 24), we also explored this region in R. paucula and compared it to those of other Ralstonia species.


==References==
==References==
[Sample reference] [http://ijs.sgmjournals.org/cgi/reprint/50/2/489 Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "''Palaeococcus ferrophilus'' gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". ''International Journal of Systematic and Evolutionary Microbiology''. 2000. Volume 50. p. 489-500.]


Edited by student of [mailto:ralarsen@ucsd.edu Rachel Larsen] and Kit Pogliano
1.Llyod, Robin. "Eureka! Bacteria Have the Midas Touch" 18 July 2006.
www.livescience.com/strangenews/060718_gold_bacteria
 
2.Larsen, Rachel and Kit Pogliano. "Outside structures 1: cell wall and membranes." BIMM 120: Introductory Microbiology. University of California, San Diego. Spring 2007.
 
3. M Mergeay. "Alcaligenes eutrophus CH34 is a facultative chemolithotroph with plasmid-bound resistance to heavy metals." J Bacteriol. April 1985
http://jb.asm.org/cgi/content/abstract/162/1/328
 
4. "Cupriavidas metallidurans CH34" JGI Microbes
http://genome.jgi-psf.org/draft_microbes/ralme/ralme.home.html
 
5. http://genome.jgi-psf.org/finished_microbes/ralme/ralme.home.html
 
6. genome.bnl.gov/sequencing/Rmetallidurans
 
7.skcen.be/sckcen_en/activities/research/radiationprotection/radiobio/ralmet
 
8. genome.jp/kegg-bin/show_organism?org=rme
 
10. M Mergeav. "Ralstonia metallidurans, a bacterium specifically adapted to toxic metals: towards a catalogue of metal-responsive genes." FEMS Microbial Rev. June 2003
http://ncbi.nlm.nih.gov/sites/entrez?
 
11. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC87738/
 
cmd=Retrieve&db=PubMed&list_uids=12829276
 
11. bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=05-33
 
12. American Chemical Society."New 'biofuel cell' produces electricity from hydrogen in plain air."26 March 2007. http://www.physorg.com/news94144517.html
 
Edited by Shu-Mei (April) Yu student of[mailto:ralarsen@ucsd.edu Rachel Larsen] and Kit Pogliano.
 
 
KMG
 
<!-- Do not edit or remove this line-->[[Category:Pages edited by students of Mary Glogowski at Loyola University]]

Latest revision as of 15:21, 7 July 2011

This is a curated page. Report corrections to Microbewiki.

A Microbial Biorealm page on the genus Ralstonia metallidurans


Classification

Higher order taxa

Kingdom: Bacteria

Phylum: Proteobacteria

Class: Beta Proteobacteria

Order:Burkholderiales

Family: Ralstoniaceae

Genus: Ralstonia

Species: R. metallidurans

Strain: CH3

Species

NCBI: Taxonomy


Ralstonia basilensis
Ralstonia campinensis
Ralstonia eutropha
Ralstonia gilardii
Ralstonia insidiosa
Ralstonia mannitolilytica
Ralstonia paucula
Ralstonia pickettii
Ralstonia respiraculi
Ralstonia solanacearum
Ralstonia syzygii
Ralstonia taiwanensis


Description and significance

Ralstonia metallidurans is a gram-negative microbe that does not form spores. It is unique in that it can fluorish in millimolar concentrations of heavy metals, such as gold, that are normally toxic to bacteria. According to discoverer Frank Reith, Ralstonia metallidurans "is able to survive in concentrations of gold that would kill most other micro-organisms" (1). Not only can these microbes withstand toxic concentrations of metals, they are found to be able to precipitate gold. Although it is unknown exactly how this process works, it is "possible that the microbe screens out gold as part of an effort to detoxify its immediate environment" (1).

Ralstonia metallidurans and other metal resistant microbes are often found in sediments with a high content of heavy metals from diverse geographical locations. The reference strain, CH34, was first discovered in 1976, from the sludge of a zinc decantation tank in Belgium that was polluted with high concentrations of several heavy metals. Frank Reith (and colleagues) at Australian National University further isolated and grew the bacteria in the lab.

The significance of this microbe lays in that its genome contains plasmids that confer resistance to heavy metals, such as Zinc, Mercury, Cadmium, Cobalt, etc. In 1992, Kostman et al. developed a PCR-ribotyping method for B. cepacia which could detect significant polymorphisms in the intergenic 16S-23S spacer of rRNA genes (7). In 1997, Shreve et al. used PCR-RFLP analysis for the 16S and 23S regions of the rRNA genes in an epidemiological study of B. cepacia infection (21). Segonds et al. used PCR-RFLP analysis of the 16S rRNA gene to differentiate Burkholderia species (20).

Genome structure

The genome of R. metallidurans CH34 has been extensively studied. It contains two large plasmids that encode for heavy metal resistance. pMOL28 (163 kb) furnishes tolerance to Nickel, Mercury, and Cobalt; pMOL30 (238 kb) confers resistance to Zinc, Cadmium, Mercury, and Cobalt (3). These plasmids are self-transmissible in homologous matings, but at low frequencies (3). The entire genome is approximately 6900 kb in size. In addition to the plasmids pMOL28 and pMOL30, it also contains two circular chromosomes (8). Furthermore, the genome encodes "8 P-type ATPase involved in metal efflux specialized in lead, cadmium, thallium and/or copper efflux, and several other mechanism involved in metal processing" (1). Together, these genetic elements contribute to the microbe's unique ability to survive in harsh environments. The amplicons of R. paucula isolates were digested with AciI and AlwI. All of the strains shared a single pattern with each of the two endonucleases. The AciI pattern was composed of eight fragments (340, ~200, 122, 119, 92, 75, 49, and 44 bp), and the AlwI pattern was composed of four fragments (418, 218, 130, and 75 bp)

Cell structure and metabolism

R. metallidurans is a gram-negative bacillus (rod shaped). Therefore, it has the structural features of gram-negative bacteria, such as cell walls containing peptidoglycan, an outer membrane containing LPS and porins, and a periplasmic space (2).

R. metallidurans is able to utilize a variety of substrates as its carbon source. It can grow autotrophically using molecular hydrogen as an energy source and carbon dioxide as its carbon source. Furthermore, in the presence of nitrate, it can grow anaerobically (6). When grown lithoautotrophically on molecular hydrogen, it forms cytoplasmic NAD-reducing and membrane bound hydrogenase. It does not grow on fructose (3) and its optimal growth temperature is 30 C (4).

Ecology

Due to its ability to withstand toxic metals, R. metallidurans has been studied to utilize this characteristic in areas of bioremediation (10). Furthermore, new findings of a lead binding protein isolated from R. metallidurans is key in preventing lead poisoning (11).

Pathology

R. metallidurans has not been found to be pathogenic to humans. However, a near relative, R. solancearum, that shares some of the metal resistant genes, has been found to cause disease in plants (10). R. paucula has been isolated from pool water, groundwater, and bottled mineral water (2, 9, 17) and from clinical specimens. Despite its low pathogenicity, it is now recognized as an opportunistic pathogen which can generate serious infections such as septicemia, peritonitis, abscess, and tenosynovitis, particularly in immunocompromised patients

Application to Biotechnology

R. metallidurans has been found to produce enzymes that may be used in constructing a fuel cell (12). These enzymes are able to oxidize hydrogen, which can ultimately result in the production of electricity. Scientists are in the process of researching this phenomenom (12).

Current Research

Currently, R. metallidurans are being studied for their potential in fuel cell production (12). Also, as mentioned above, this microbe has the unique ability to precipitate gold. Current research is trying to better understand this interesting characteristic(1). Furthermore, R. metallidurans has been studied for its use in the prevention of lead contamination by the fluorescent signaling of its lead binding protein (11). Recently, several authors have reported the use of PCR-ribotyping (3, 5, 7, 8, 12, 22, 23) and PCR-restriction fragment length polymorphism (PCR-RFLP) analysis (20, 21) for strain differentiation within various bacterial species. Thus, an evaluation for the ability of these two techniques to distinguish between R. paucula strains and between strains belonging to other Ralstonia species (R. eutropha, R. pickettii, R. gilardii, and R. solanacearum) is going on. As the ribosomal DNA (rDNA) intergenic spacer can contain genes coding for tRNA (15, 24), we also explored this region in R. paucula and compared it to those of other Ralstonia species.

References

1.Llyod, Robin. "Eureka! Bacteria Have the Midas Touch" 18 July 2006. www.livescience.com/strangenews/060718_gold_bacteria

2.Larsen, Rachel and Kit Pogliano. "Outside structures 1: cell wall and membranes." BIMM 120: Introductory Microbiology. University of California, San Diego. Spring 2007.

3. M Mergeay. "Alcaligenes eutrophus CH34 is a facultative chemolithotroph with plasmid-bound resistance to heavy metals." J Bacteriol. April 1985 http://jb.asm.org/cgi/content/abstract/162/1/328

4. "Cupriavidas metallidurans CH34" JGI Microbes http://genome.jgi-psf.org/draft_microbes/ralme/ralme.home.html

5. http://genome.jgi-psf.org/finished_microbes/ralme/ralme.home.html

6. genome.bnl.gov/sequencing/Rmetallidurans

7.skcen.be/sckcen_en/activities/research/radiationprotection/radiobio/ralmet

8. genome.jp/kegg-bin/show_organism?org=rme

10. M Mergeav. "Ralstonia metallidurans, a bacterium specifically adapted to toxic metals: towards a catalogue of metal-responsive genes." FEMS Microbial Rev. June 2003 http://ncbi.nlm.nih.gov/sites/entrez?

11. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC87738/

cmd=Retrieve&db=PubMed&list_uids=12829276

11. bnl.gov/bnlweb/pubaf/pr/PR_display.asp?prID=05-33

12. American Chemical Society."New 'biofuel cell' produces electricity from hydrogen in plain air."26 March 2007. http://www.physorg.com/news94144517.html

Edited by Shu-Mei (April) Yu student ofRachel Larsen and Kit Pogliano.


KMG