''Pseudomonas protegens'' are widespread

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

, plant-protecting

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

. Some of the strains of this novel bacterial species (CHA0 and Pf-5, for example) previously belonged to '' P. fluorescens''. They were reclassified since they seem to cluster separately from other fluorescent ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative bacteria belonging to the family Pseudomonadaceae in the class Gammaproteobacteria. The 348 members of the genus demonstrate a great deal of metabolic diversity and consequently are able to colonize a ...

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

'' species complexes '' P. fluorescens'', '' 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 '' P. fluorescens'', ''Pseudomonas protegens'' is a typical soil microorganism with an extremely versatile

metabolism Metabolism (, from ''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 cellular processes; the co ...

, and can be isolated from roots of various plant species. The microbe is strictly

aerobe An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment. The ability to exhibit aerobic respiration may yield benefits to the aerobic organism, as aerobic respiration yields more energy than anaerobic ...

(no reduction of

nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wa ...

) and

oxidase In biochemistry, an oxidase is an oxidoreductase (any enzyme that catalyzes a redox reaction) that uses dioxygen (O2) as the electron acceptor. In reactions involving donation of a hydrogen atom, oxygen is reduced to water (H2O) or hydrogen peroxid ...

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

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

The name

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

Greek Greek may refer to: 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 of all kno ...

: ''ψευδο'' 'false') and ''monas'' (

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

: ''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 ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

(described in detail for '' P. fluorescens''), ''Pseudomonas protegens'' was discovered to display toxicity towards certain insects upon oral ingestion or injection into the

hemolymph Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph c ...

. 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 Hetero ...

''.

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