Pseudomonas entomophila

A Microbial Biorealm page on the genus Pseudomonas entomophila

Classification

Higher order taxa

Bacteria, Proteobacteria, Gammaproteobacteria, Pseudomonadales, Pseudomonadaceae, Pseudomonas⁴

Genus

Pseudomonas entomophila⁴

NCBI: Taxonomy

Description and significance

Pseudomonas entomophila is a Gram negative bacteria, found in soil, aquatic, or rhizosphere environments. It was first isolated from the species Drosophila melanogaster. Once ingested, causes lethality in Drosophila melanogaster larvae and adults. Pseudomonas entomophila's significance is that its the first known Pseudomonas strain to be pathogenic in Drosophila melanogaster, while being absent of a type III secretion system.³ Pseudomonas entomophila's genome encodes insecticidal toxins, a diffusible haemolytic activity, lipases, extracellular proteases, and potential adhesions which cluster with type I or II secretion system proteins. Being relatively harmless to plant life, Pseudomonas entomophila may be used for future insecticides.¹

Genome structure

Pseudomonas entomophila's DNA is a single circular chromosome with the length consisting of 5,888,780 nucleotides. Its replicon type is a chromosome. 5,169 coding sequencings have been discovered in its genome along with 107 genes encoding RNA, while 3,466 genes have been associated with predicted functions.⁵

Cell structure and metabolism

A gram negative bacteria with flagella present. Structural proteins consist of three proteins PSEEN0141, PSEEN2177, and PSEEN3946 involved in adhesion to host surfaces and promoting colonization. Its metabolism includes the pentose phosphate pathway, the Entner-Doudoroff pathway, the tricarboxylic acid cycle, and an incomplete Embden-Meyerhof-Parnas pathway due to the absence of 6-phophofructokinase. Its genome encodes for hydrolytic activities, lipases, proteases, a set of 19 uncharacterized hydrolases involved in the degradation of polymers found within the soil.²

Ecology

Found in diverse environments such as the soil, aquatic, rhizosphere, and a pathogenic interaction with Drosophila melanogaster. D. melanogaster maintains a hostile environment for microbes by secreting antimicrobial factors such as lysozymes and other digestive enzymes. P. entomophila's genome consists four catalases, two superoxide dismutases, three hydroperoxide reductases, and eleven glutathione-S-transferases, which are involved in resistance to oxidative stress produced by D. melanogaster to prevent microbial proliferation within the gut.

Pathology

Pseudomonas entomophila's persistence within the gut initiates a local and systemic immune response in the insect. Virulence factor found to be lethality among Drosophila melanogaster larvae and adults, as well as other insects.⁶ Its genome is devoid of genes encoding enzymes able to breakdown plant cell walls, confirming its nonpathogenesis in plants. Pseudomonas entomophila produces three TccC-type compounds PSEEN2485, PSEEN2697, and PSEEN2788, all of which are insecticidal toxins. It also secretes a diffusible hemolytic activity which may be involved in pathogenicity in insects. Bacterial hemolysins act as exotoxins that cell rupture by attacking blood cell membranes. It also produces proteases, three serine proteases PSEEN3027, PSEEN3028, PSEEN4433 and an alkaline protease PSEEN1550. Proteases contribute to the virulence among different species.²

Application to Biotechnology

Pseudomonas entomophila's characteristic pathogenicity in insects, combined with its nonpathogenicity in plants suggests great potential for a biological insecticidal in agriculture. It can be used to strictly target insects while being harmless to plant life. Also, its complete genome represents a type of template for further studies in pathogenic properties and host-pathogen interactions.

Current Research

Sequencing the entire genome of Pseudomonas entomophila to obtain information on various proteins present and involved in metabolism, transport, regulation, and structure, toxins and virulence factors produced to survive in different environments within its given ecology.

Pseudomonas entomophila's pathogenic relationship mainly with Drosophila melanogaster as well as other insects from other orders. Local and systemic immune response, followed by lethality upon ingestion among Drosophila melanogaster adults and larvae. Interests its toxins, proteases, and hemolysins that contribute to its virulence and pathogenic nature.

Possibilities for biological benefits as insecticides within agriculture. Nonpathogenic behavior among plants discovered from its lack of enzymes within its genome capable of degrading plant cell walls. However, multiple proteins and toxins present in genome that serve as pathogens leading to virulence among certain insects and factors that eliminate competition among neighboring microbes within soil, aquatic, and rhizosphere environments.

References

1. PubMed=16699499; [ NCBI , Israel , Japan ]

2. Vodovar N., Vallenet D., Cruveiller S., Rouy Z., Barbe V., Acosta C., Cattolico L., Jubin C., Lajus A., Segurens B., Vacherie B., Wincker P., Weissenbach J., Lemaitre B., Medigue C., Boccard F. "Complete genome sequence of the entomopathogenic and metabolically versatile soil bacterium Pseudomonas entomophila." Nat. Biotechnol. 24:673-679(2006).

3. EBI Proteome Analysis page

4. NCBI: Taxonomy

5. Kyoto Encyclopedia of Genes and Genomes (KEGG)

6. Proceedings of the National Academy of Sciences of the United States of America (PNAS) "Drosophila host defense after oral infection by an entomopathogenic Pseudomonas species"

7. Comprehensive Microbial Resource (CMR) "Pseudomonas entomophila L48 Genome Page"

Edited by Jason Kim, student of Rachel Larsen and Kit Pogliano