Pseudomonadaceae
Encyclopedia
The Pseudomonadaceae is a family
of bacteria that includes the genera Azomonas
, Azomonotrichon, Azorhizophilus, Azotobacter
, Cellvibrio, Mesophilobacter, Pseudomonas
(the type genus), Rhizobacter, Rugamonas, and Serpens. The Azotobacteriaceae were recently published as belonging in this family as well.
pseudo (ψευδο 'false') and monas (μονος 'a single unit'). The term "monad" was used in the early history of microbiology to denote single-celled organisms.
Because of their widespread occurrence in nature, the pseudomonads were observed early in the history of microbiology
. The generic name Pseudomonas created for these organisms was defined in rather vague terms in 1894 as a genus of Gram-negative, rod-shaped and polar-flagella bacteria. Soon afterwards, a very large number of species was assigned to the genus
. Pseudomonads were isolated from many natural niches and a large number of species names was originally assigned to the genus. New methodology and the inclusion of approaches based on the studies of conservative macromolecules have reclassified many strains.
Pseudomonas aeruginosa
is increasingly recognized as an emerging opportunistic pathogen of clinical relevance. Studies also suggest the emergence of antibiotic resistance in P. aeruginosa.
In the year 2000, the complete genome sequence of a Pseudomonas
species was determined; more recently the sequence of other strains have been determined including P. aeruginosa
strains PAO1 (2000), P. putida
KT2440 (2002), P. fluorescens Pf-5 (2005), P. fluorescens PfO-1 and P. entomophila L48. Several pathovars of Pseudomonas syringae
have been sequenced, including pathovar tomato DC3000 (2003), pathovar syringae B728a (2005), and pathovar phaseolica 1448A (2005).
The presence of oxidase, polar flagella and inability to carry out fermentation differentiate Pseudomonads from Enterobacteriaceae
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Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of bacteria that includes the genera Azomonas
Azomonas
Azomonas are typically motile, oval to spherical, and secrete large quantities of capsular slime. They are distinguished from Azotobacter by their inability to form cysts, but like Azotobacter they can biologically fix nitrogen under aerobic conditions .-Etymology:The name Azomonas derives...
, Azomonotrichon, Azorhizophilus, Azotobacter
Azotobacter
Azotobacter is a genus of usually motile, oval or spherical bacteria that form thick-walled cysts and may produce large quantities of capsular slime. They are aerobic, free-living soil microbes which play an important role in the nitrogen cycle in nature, binding atmospheric nitrogen, which is...
, Cellvibrio, Mesophilobacter, Pseudomonas
Pseudomonas
Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...
(the type genus), Rhizobacter, Rugamonas, and Serpens. The Azotobacteriaceae were recently published as belonging in this family as well.
History
Pseudomonad literally means 'false unit', being derived from the GreekAncient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
pseudo (ψευδο 'false') and monas (μονος 'a single unit'). The term "monad" was used in the early history of microbiology to denote single-celled organisms.
Because of their widespread occurrence in nature, the pseudomonads were observed early in the history of microbiology
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
. The generic name Pseudomonas created for these organisms was defined in rather vague terms in 1894 as a genus of Gram-negative, rod-shaped and polar-flagella bacteria. Soon afterwards, a very large number of species was assigned to the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. Pseudomonads were isolated from many natural niches and a large number of species names was originally assigned to the genus. New methodology and the inclusion of approaches based on the studies of conservative macromolecules have reclassified many strains.
Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
is increasingly recognized as an emerging opportunistic pathogen of clinical relevance. Studies also suggest the emergence of antibiotic resistance in P. aeruginosa.
In the year 2000, the complete genome sequence of a Pseudomonas
Pseudomonas
Pseudomonas is a genus of gammaproteobacteria, belonging to the family Pseudomonadaceae containing 191 validly described species.Recently, 16S rRNA sequence analysis has redefined the taxonomy of many bacterial species. As a result, the genus Pseudomonas includes strains formerly classified in the...
species was determined; more recently the sequence of other strains have been determined including P. aeruginosa
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...
strains PAO1 (2000), P. putida
Pseudomonas putida
Pseudomonas putida is a gram-negative rod-shaped saprotrophic soil bacterium. Based on 16S rRNA analysis, P. putida has been placed in the P. putida group, to which it lends its name....
KT2440 (2002), P. fluorescens Pf-5 (2005), P. fluorescens PfO-1 and P. entomophila L48. Several pathovars of Pseudomonas syringae
Pseudomonas syringae
Pseudomonas syringae is a rod shaped, Gram-negative bacterium with polar flagella. It is a plant pathogen which can infect a wide range of plant species, and exists as over 50 different pathovars, all of which are available to legitimate researches via international culture collections such as the...
have been sequenced, including pathovar tomato DC3000 (2003), pathovar syringae B728a (2005), and pathovar phaseolica 1448A (2005).
Distinguishing characteristics
- Oxidase positive - this is due to the presence of cytochrome c oxidase enzyme
- Non-fermentative
- Many metabolise glucose by the Entner Doudoroff pathway mediated by the following enzymes - 6 phosphoglyceraldehyde dehydrogenase and aldolase
- Polar flagella, enabling motility
- Many members produce derivatives of the fluorescent pigment pyoverdinFluoresceinFluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....
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The presence of oxidase, polar flagella and inability to carry out fermentation differentiate Pseudomonads from Enterobacteriaceae
Enterobacteriaceae
The Enterobacteriaceae is a large family of bacteria that includes many of the more familiar pathogens, such as Salmonella, Escherichia coli, Yersinia pestis, Klebsiella and Shigella. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the...
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