The Pseudomonadaceae are a

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

which includes the genera '' Azomonas'', '' Azorhizophilus'', '' Azotobacter'', '' Mesophilobacter'', '' Pseudomonas'' (the type genus), and '' Rugamonas''. The family Azotobacteraceae was recently reclassified into this family.

History

Pseudomonad literally means false unit, being derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''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 () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, ...

. 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-flagellated bacteria. Soon afterwards, a large number of species was assigned to the genus. Pseudomonads were isolated from many natural niches. New methodology and the inclusion of approaches based on the studies of conservative macromolecules have reclassified many species. ''

Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic– facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aer ...

'' is increasingly recognized as an emerging opportunistic pathogen of clinical relevance. Studies also suggest the emergence of

antibiotic resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistanc ...

in ''P. aeruginosa''. In 2000, the complete genome of a '' Pseudomonas'' species was sequenced; more recently, the genomes of other species have been sequenced, including ''P. aeruginosa'' 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).

Distinguishing characteristics

* Oxidase positive – due to the presence of the enzyme cytochrome c oxidase. * Nonfermentative * Many metabolise glucose by the Entner Doudoroff pathway mediated by 6-phosphoglyceraldehyde dehydrogenase and aldolase * Polar flagella, enabling motility * Many members produce derivatives of the fluorescent pigment pyoverdin The presence of oxidase and polar flagella and inability to carry out fermentation differentiate pseudomonads from the Enterobacteriaceae.Krieg, N.R. (Ed.) (1984) Bergey's Manual of Systematic Bacteriology, Volume 1. Williams & Wilkins.

References

Pseudomonadales {{Pseudomonadales-stub