Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane.
Pseudomonas is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 validly described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a wide range of niches. Their ease of culture in vitro and availability of an increasing number of Pseudomonas strain genome sequences has made the genus an excellent focus for scientific research; the best studied species include P. aeruginosa in its role as an opportunistic human pathogen, the plant pathogen P. syringae, the soil bacterium P. putida, and the plant growth-promoting P. fluorescens, P. lini, P. migulae, and P. graminis.
Pseudomonas fluorescens is a common Gram-negative, rod-shaped bacterium. It belongs to the Pseudomonas genus; 16S rRNA analysis as well as phylogenomic analysis has placed P. fluorescens in the P. fluorescens group within the genus, to which it lends its name.
Pseudomonas fragi is a psychrophilic, Gram-negative bacterium that is responsible for dairy spoilage. Unlike many other members of the genus Pseudomonas, P. fragi does not produce siderophores. Optimal temperature for growth is 30 °C, however it can grow between 0 and 35 °C. Based on 16S rRNA analysis, P. fragi has been placed in the P. chlororaphis group.
Pseudomonas avellanae is a Gram-negative plant pathogenic bacterium. It is the causal agent of bacterial canker of hazelnut. Based on 16S rRNA analysis, P. avellanae has been placed in the P. syringae group. This species was once included as a pathovar of Pseudomonas syringae, but following DNA-DNA hybridization, it was instated as a separate species. Following ribotypical analysis Pseudomonas syringae pv. theae was incorporated into this species.
Pseudomonas tolaasii is a species of Gram-negative soil bacteria that is the causal agent of bacterial blotch on cultivated mushrooms. It is known to produce a toxin, called tolaasin, which is responsible for the brown blotches associated with the disease. It also demonstrates hemolytic activity, causing lysis of erythrocytes. Based on 16S rRNA analysis, P. tolaasii has been placed in the P. fluorescens group.
Pseudomonas mendocina is a Gram-negative environmental bacterium that can cause opportunistic infections, such as infective endocarditis and spondylodiscitis, although cases are very rare. It has potential use in bioremediation as it is able to degrade toluene. Based on 16S rRNA analysis, P. mendocina has been placed in the P. aeruginosa group.
Pseudomonas libanensis is a Gram-negative, rod-shaped, fluorescent, motile bacterium isolated from natural springs in Lebanon. Based on 16S rRNA analysis, P. libanensis has been placed in the P. fluorescens group.
Pseudomonas cedrina is a Gram-negative, rod-shaped bacterium isolated from spring waters in Lebanon. Based on 16S rRNA analysis, P. cedrina has been placed in the P. fluorescens group.
Pseudomonas orientalis is a Gram-negative, rod-shaped bacterium isolated from spring waters in Lebanon. Based on 16S rRNA analysis, P. orientalis has been placed in the P. fluorescens group.
Pseudomonas mandelii is a fluorescent, Gram-negative, rod-shaped bacterium isolated from natural spring waters in France. Based on 16S rRNA analysis, P. mandelii has been placed in the P. fluorescens group.
Pseudomonas jessenii is a fluorescent, Gram-negative, rod-shaped bacterium isolated from natural mineral waters in France. The type strain is CIP 105274.
Pseudomonas migulae is a fluorescent, Gram-negative, rod-shaped bacterium isolated from natural mineral waters in France. This bacterium has also been isolated from endophytic tissues of lodgepole pine trees growing on gravel mining sites with potential to perform biological nitrogen fixation and plant growth promotion. Based on 16S rRNA analysis, P. migulae has been placed in the P. fluorescens group.
Pseudomonas gessardii is a fluorescent, Gram-negative, rod-shaped bacterium isolated from natural mineral waters in France. Based on 16S rRNA analysis, P. gessardii has been placed in the P. fluorescens group.
Pseudomonas resiniphila is a Gram-negative soil bacterium that grows on pulp mill effluents with resin acids. It was first isolated in Canada.
Pseudomonas vancouverensis is a Gram-negative soil bacterium that grows on pulp mill effluents with resin acids. It was first isolated in Canada.
Pseudomonas nitroreducens is an aerobic, Gram-negative soil bacterium first isolated from oil brine in Japan. It is able to synthesise polyhydroxybutyrate homopolymer from medium chain length fatty acids. Based on 16S rRNA analysis, P. nitroreducens has been placed in the P. aeruginosa group.
The term skin flora refers to the microorganisms which reside on the skin, typically human skin.
Isopimaric acid (IPA) is a toxin which acts as a large conductance Ca2+-activated K+ channel (BK channel) opener.
Rhamnolipids are a class of glycolipid produced by Pseudomonas aeruginosa, amongst other organisms, frequently cited as bacterial surfactants. They have a glycosyl head group, in this case a rhamnose moiety, and a 3-(hydroxyalkanoyloxy)alkanoic acid (HAA) fatty acid tail, such as 3-hydroxydecanoic acid.
