Pseudomonas stutzeri: Difference between revisions
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Revision as of 20:09, 12 April 2012
Classification
Domain Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Pseudomonadales; family Pseudomonadaceae NCBI
Species
Pseudomonas stutzeri
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NCBI: [1] |
Description and Significance
Individual P. stutzeri are rod-shaped and have a single polar flagellum. Cells are approximately 1-3um long and 0.5um in diameter. Colonies are unusually formed and are disc shaped with ridges radiating from the center (see picture).
P. stutzeri lives in very diverse environments, including soils and aquatic habitats. In soil, the organism is present in the rhizosphere of
Genome Structure
Description of the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?
Three clinical strains of Psuedomonas stutzeri have been completely sequenced, providing a great deal of information about the content of the genome. The genome is encoded on a singular chromosome which is circular. No plasmids were detected in any of the three sequences. The length of the chromosome of one particular strain was 4,547,930 bp, with the two other strains both being slightly longer. Genes for denitrification were found in two strains, but were absent in a third. All three strains contained genes encoding for benzoate and catechol degradation, as well as chemotaxis. -may want to go into greater detail about the differences found in the genomes between the three sequenced strains?
Cell Structure, Metabolism and Life Cycle
Interesting features of cell structure; how it gains energy; what important molecules it produces.
The cells are rod-shaped, with a single polar flagellum, and they are 1-3um by 0.5um.
Pseudomonas stutzeri are generally chemoorganoheterotrophs. This means that their energy source is dissolved organic molecules such as sugars, starches, amino acids, acetate, and pyruvate. It also means that the organic molecules are their carbon source as well, rather than fixing and reducing their own carbon dioxide.
P. stutzeri are also denitrifiers. In other words they use Nitrate as an electron acceptor in their metabolism in place of oxygen. Nitrates undergo a four-step process in the cell, being converted to Nitrite, Nitric Oxide, Nitrous Oxide, and finally Dinitrogen gas. P. stutzeri are used as a model organism for studying Denitrification.
However, P. stutzeri, being found in a wide variety of habitats, is also a very metabolically diverse species. A variety of metabolisms have been observed in strains linked phylogenetically into the P. stutzeri species. For example, some strains are able to use Thiosulfate as an energy source, producing H2SO4. Such strains are technically chemolithoautotrophic, since they use an inorganic compound as an energy and electron source.
Others have been shown to fix nitrogen in environments such as the roots of rice. In fact, some strains have even been shown to grow diazotrophically (in the absence of any nitrogen source other than N2 gas to fix).
Other strains are able to oxidize either phosphite or hypophosphite in the absence of any other phosphorous source. Still other strains found in high-metal environments such as mines and polluted soil have been shown to resist those metals. There are records of resistance of silver, zinc, and nickel, and the mechanisms of resistance are generally not well understood.
It should be noted that despite this metabolic diversity (as well as genetic diversity), some common phenotypic characters are observed in all cases, and the species can be keyed out in the lab by those characteristics.
Ecology and Pathogenisis
The versatility of P. stutzeri's metabolism allows it to grow in a variety of conditions. It can be found in the soil and rhizosphere, where strains are known to be nitrogen fixers, thereby participating in a symbiosis with the plant root system of many commonly grown plants including wheat, barley, and rice.
Some strains of P. stutzeri are of marine origin, and contribute to the nitrogen cycle by degrading nitrogen oxides to atmospheric nitrogen. Some strains have even been found present near hydrothermal vents in the Marianas Trench, the deepest part of the ocean.
P. stutzeri has also been found in wastewater, where its unique ability to degrade some anthropogenic compounds may have relevance to bioremediation.
P. Stutzeri is an opportunistic pathogen. It has been isolated from clinical samples and has been found to cause infection in humans, though rarely. Many species of Pseudomonas have been shown to cause skin infections (Ecthyma gangrenosum) including P. stutzeri. Other cases include infections of prosthetic bone replacements (reference). All but two cases of P. stutzeri have been treated successfully with antibiotics. The two cases that antibiotic treatment failed, resulted in death of the patient. However, it was unclear whether the bacterial infection was the ultimate cause of death, as all patients infected with P. stutzeri had other health conditions prior to infection.
References
Author
This page still under construction. Authored by William Baughman, Kathleen Balaze, and Andrew Bruce, students of Prof. Jay Lennon at Michigan State University.
Web of Science cited ref search using the Lalucat et al paper: http://apps.webofknowledge.com.proxy1.cl.msu.edu/summary.do?SID=1D99a2NleNnO%408mFHIM&product=WOS&qid=6&search_mode=CitedRefIndex
Also, hey guess what it’s been sequenced! Just this last November! http://jb.asm.org.proxy1.cl.msu.edu/content/193/21/6095.full
