Pseudomonas aeruginosa

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Classification

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Scientific classification
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Binomial name
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The genus Pseudomonas holds about sixty different types of species in the kingdom classified as bacteria. The species Pseudomonas aeruginosa is classified as a gram-negative bacterium[1]|. Most Pseudomonas aeruginosa are categorized as obligate aerobes, however sometimes in certain environmental conditions, the bacteria acts as a facultative anaerobe. Furthermore, because of the way it obtains its energy, it is considered to be a chemoheterotroph. (Willey)

Description and significance

The Pseudomonas genus includes bacteria that are straight or slightly curved rods. P. aeruginosa is a rod-shaped bacterium. Its size ranges from 0.5 to 1.0mm by 1.5 to 5.0mm in terms of its length and width. P. aeruginosa is a well-studied species due to its high level pathogenicity and its significant role in human disease. The organism can thrive under many environmental conditions, such as soil, water and even hospital environments.

Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.

Genome structure

A genome contains a microbe’s hereditary information that is encoded in DNA, which is made up of many genes. This microbe’s genome is a single circular chromosome at 6,264,403 base pairs (Bp), which is 6.3 million bases (Mb) and contains 5,570 predicted genes on one chromosome (Stover, et al). The P. aeruginosa almost the largest genome sequenced as compared to other bacterial genomes that have been sequenced. Due to its large genome size, P. aeruginosa has tremendous genetic density, allowing it to form biofilms. It utilizes quorum sensing (group symbiosis) to achieve its resistance against microbial agents in most cases. They also have metabolic plasmids that are about 75-230 kbp in size and are involved in degrading substances such as sugars.

Describe the size and content of the genome. Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?

Cell structure and metabolism

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Ecology

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Pathology

P. aeruginosa can infect animals, plants and also humans. They cause disease in humans who are already ill, infecting those patients with low resistance in their bodies. P. aeruginosa are opportunistic pathogens and cause infection in patients who are diagnosed with cystic fibrosis, have lower respiratory tract infections, surgical wounds, urinary tract infections, skin infections i.e:(dermatitis), and even in patients who have cancer i.e: blood cancer (Willey). It causes nosocomial infection in patients as this bacterium can grow anywhere where enough nutrients and enough moisture are found.

An opportunistic pathogen, P. aeruginosa produces a thick biofilm and due to its dense colonization, it is able to resist many antibiotics, disinfectants, as well as UV light and infected patients can therefore be difficult to treat. Another factor that contributes to P. aeruginosa resistance is its gram negative cell wall that is composed of three layers; the inner plasma membrane, peptidoglycan, and its outer membrane. This high level of resistance in P. aeruginosa can be of consequence and dangerous to a patient’s health.

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

Willey, Sherwood, Woolverton. 2008. Prescott, Harley, and Klein’s Microbiology, Seventh Edition. New York 10020: McGraw-Hill Companies, Inc. 1088p.

C.K. Stover, et al. Complete genome sequence of Pseudomonas aeruginosa PA01, an opportunistic pathogen.

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.