Pseudomonadaceae

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Pseudomonadaceae
Pseudomonas aeruginosa 01.jpg
P. aeruginosa colonies on an agar plate.
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Pseudomonadaceae
Winslow et al., 1917
Genera

Azomonas
Azomonotrichon
Azorhizophilus
Azotobacter
Cellvibrio
Mesophilobacter
Pseudomonas
Rhizobacter
Rugamonas
Serpens

The Pseudomonadaceae are a family of bacteria that includes the genera Azomonas, Azomonotrichon, Azorhizophilus, Azotobacter, Cellvibrio, Mesophilobacter, Pseudomonas (the type genus), Rhizobacter, Rugamonas, and Serpens.[1][2] The Azotobacteriaceae were recently published as belonging in this family as well.[3]

History[edit]

Pseudomonad literally means 'false unit', being derived from the 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. 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.[4]

In 2000, the complete genome sequence of a Pseudomonas species was determined; more recently, the sequences 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).[2]

Distinguishing characteristics[edit]

  • 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 6-phosphoglyceraldehyde dehydrogenase and aldolase
  • Polar flagella, enabling motility
  • Many members produce derivatives of the fluorescent pigment pyoverdin[5]

The presence of oxidase and polar flagella and inability to carry out fermentation differentiate pseudomonads from Enterobacteriaceae:.[6]

References[edit]

  1. ^ Skerman, McGowan and Sneath (editors): Approved Lists of Bacterial Names. Int. J. Syst. Bacteriol., 1980, 30, 225-420.
  2. ^ a b Cornelis P (editor). (2008). Pseudomonas: Genomics and Molecular Biology (1st ed.). Caister Academic Press. ISBN 1-904455-19-0. [1]. 
  3. ^ Rediers H, Vanderleyden J, De Mot R (2004). "Azotobacter vinelandii: a Pseudomonas in disguise?". Microbiology 150 (Pt 5): 1117–9. doi:10.1099/mic.0.27096-0. PMID 15133068. 
  4. ^ Carmeli, Y; Troillet, N; Eliopoulos, GM; Samore, MH (1999). "Emergence of Antibiotic-Resistant Pseudomonas aeruginosa: Comparison of Risks Associated with Different Antipseudomonal Agents". Antimicrobial agents and chemotherapy 43 (6): 1379–82. PMC 89282. PMID 10348756. 
  5. ^ Meyer J (2000). "Pyoverdines: pigments, siderophores and potential taxonomic markers of fluorescent Pseudomonas species". Arch Microbiol 174 (3): 135–42. doi:10.1007/s002030000188. PMID 11041343. 
  6. ^ Krieg, N.R. (Ed.) (1984) Bergey's Manual of Systematic Bacteriology, Volume 1. Williams & Wilkins. ISBN 0-683-04108-8