''Pseudomonas protegens'' are widespread

Gram-negative 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 ...

, plant-protecting

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 among ...

. Some of the strains of this novel bacterial species (CHA0 and Pf-5, for example) previously belonged to ''

P. fluorescens ''Pseudomonas fluorescens'' is a common Gram-negative, rod-shaped bacterium. It belongs to the ''Pseudomonas'' genus; 16S ribosomal RNA, 16S rRNA analysis as well as phylogenomic analysis has placed ''P. fluorescens'' in the ''P. fluorescens'' gr ...

''. They were reclassified since they seem to cluster separately from other fluorescent ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...

'' species. ''P. protegens'' is phylogenetically related to the ''

'' species complexes ''

'', '' P. chlororaphis'', and '' P. syringae''. The bacterial species characteristically produces the antimicrobial compounds pyoluteorin and 2,4-diacetylphloroglucinol (DAPG) which are active against various plant pathogens.

General characteristics

Like ''

'', ''Pseudomonas protegens'' is a typical soil microorganism with an extremely versatile

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

, and can be isolated from roots of various plant species. The microbe is strictly aerobe (no reduction of

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

) and

oxidase In biochemistry, an oxidase is an enzyme that catalyzes oxidation-reduction reactions, especially one involving dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydro ...

-positive. The bacterium grows at temperatures between 4 °C and 36 °C, and has one to three

flagella A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have f ...

The name

The word ''Pseudomonas'' means 'false unit', being derived from the Greek words ''pseudo'' (

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 ...

: ''ψευδο'' 'false') and ''monas'' (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

: ''monas'', fr.

: ''μονάς/μονάδα'' 'a single unit'). The species name 'protegens' refers to the bacterium's ability to protect plants from soil-borne phytopathogens.

Genome sequencing projects

The genome of ''P. protegens'' strain Pf-5 has been sequenced and published.

Biocontrol properties

''Pseudomonas protegens'' has been studied for more than twenty years for its biocontrol properties. Most studies have been carried out with the model strains CHA0 and Pf-5.

Insecticidal activity

In addition to efficiently protect plant roots against phytopathogenic

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

(described in detail for ''

''), ''Pseudomonas protegens'' was discovered to display toxicity towards certain insects upon oral ingestion or injection into the

hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...

. The insecticidal activity of the bacterium was found to be in part due to the production of an insect toxin (FitD), which is similar to a well-known protein toxin ( Mcf) produced by ''

Photorhabdus luminescens ''Photorhabdus luminescens'' (previously called ''Xenorhabdus luminescens'') is a Gammaproteobacterium of the family Morganellaceae, and is a lethal pathogen of insects. It lives in the gut of an entomopathogenic nematode of the family Heteror ...

''.

References

External links

www.genome.jp, the Pf-5 genomeType strain of ''Pseudomonas protegens'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q7255092 Pseudomonadales Bacteria described in 2011