Pseudoalteromonas atlantica

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Pseuderomonas Atlantica A Microbial Biorealm page on the genus Pseudoalteromonas atlantica


Higher order taxa

Bacteria; Proteobacteria; Gammaproteobacteria; Alteromonadales; Pseudoalteromonadaceae; Pseudoalteromonas Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]


	Pseudoalteromonas atlantica T6c

Description and significance

Credit: SEM picture by Chandra Carpenter at the University of Georgia

Pseudoalteromonas atlantica was first isolated from a marine algae in the Antarctic coastal marine environment. It is a rod-shaped, motile, gram-negative bacteria that is also found in the ocean world wide. The bacteria is motile through the means of a single polar flagellum, which helps it move back and forth between solid surfaces and the open ocean in search of food sources. The bacterial cells usually occur singly or in pairs. It obtains energy through chemoorganotrophic mechanisms. It is also biofilm-forming bacteria, which becomes important for bioremediation. It usually is found with marine eukaryotic hosts, such as crabs and seaweed. The genome of Pseudoalteromonas atlantica was sequenced due to its production of acidic extracellular polysaccharide during biofilm formation that shows potential in element recycling, detoxification, and materials production.

Genome structure

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

The size of its genome is 5.187007 megabases, and its GC content is 45%.

Cell structure and metabolism

Pseudoalteromonas is psychrotrophic, as well as chemoorganotrophic. It is capable of aerobic metabolism for energy, but not fermentation. Some important molecules it produces include acidic extracellular polysaccharide(EPS), enzymes that hydrolyze agar, alginate, and carrageenan(such as agarase), signalling molecules, such as homoserine lactones, and proteases. It produces EPS in large amounts in order to concentrate nutrients and provide substrates within its biofilm for other marine microorganisms. In order to do this, it gains energy for EPS production by colonizing solid surfaces quickly, using its secreted enzymes to process and take up substrates. Another interesting ability of this bacteria is that it has the ability to switch adhesin extracellular polysaccharide on and off. The on-off switch is essential to this bacteria's life cycle because of its need to migrate from open ocean to solid surface. Adhesins are switched off when the bacteria needs to loose its attachments to a solid surface and travel the ocean. Once a favorable surface is found, the bacteria needs adhesin for attachment. After attachment, it begins to form biolfilms.

Pseudoalteromonas atlantica grows on D-glucose, D-mannitol, and maltose, and produces acid from glucose, maltose, galactose, and mannitol, and is capable of gelatin and casein hydrolysis. It can not metabolize DL-malate, D-sorbitol, or m-hydroxybenzoate, and does not perform nitrate reduction, indole production,anr argine dihydrolase activity. This particular strain is susceptible to all antibiotics.


Pseudoalteromonas atlantica's production of acidic extracellular polysaccharide in its biofim is particularly useful in bioremediation. The biofilm can be important in controlling toxic metal concentrations in marine environments because it can absorb 20-40% of trace metal lead. The bacteria has an unusual ability to regulate its EPS production. It has a DNA recombination system that involves reversible insertion of a mobile element, called IS 492. The insertion of IS 492 at an E{S site makes variable expressions of EPS possible. This system is responsive to changes in environmental conditions, therefore the bacteria can regulate its production of EPS in terms of the present environmental condition.


Slide A= hemocyte monolayers after 30 min of incubation with 100 μl of saline Slide B= 100 μl of undiluted P. atlantica ECP Slide C = 100 μl of a solution containing 5 μg of purified LPS from P. atlantica bacteria

Pseudoalteromonas atlantica has been shown to cause shell disease-infected edible crabs. Studies show that the extracellular products or ECP of Pseudoalteromonas atlantica causes rapid death when injected into healthy crabs. ECP functions by causing rapid decline in hemocytes. The blood cells would begin to clump together(as shown in slide B). The diseased crabs show symptoms such as limb paralysis, eyestalk retraction, and marked decrease or lack of antennal sensitivity. These symptoms suggest an attack of the nervous system. ECP is not inactivated with high heat treatments or proteinase K digestion. The lipopolysaccharide(LPS) of Pseudoalteromonas atlantica was studied as a possible candidate for the main virulence factor. LPS was injected into healthy crabs and shown to cause the same symptoms and eventual death. However, with injection of LPS, no decline of hematocytes was observed. Instead of clumping, the hematocytes degranulated (shown in slide C) and eventually lysed. Results show that LPS from Pseudalteromonas atlantica is the main virulence factor for edible crabs.

There are no studies that show that Pseudoalteromonas atlantica is in any way harmful to humans.

Current Research

One most recent research on Pseudoalteromonas atlantica was done by Higgins, Carpenter, and Karls in the Department of Microbiology of the University of Georgia. These researchers found that the precise excision of mobile element IS492 on the P. atlantica chromosome regulated the EPS production on-off switch. -frequency of transposase-dependent precise excision is very high -this results in nonmutagenic repair of donor DNA, which is unusual for transposable elemnts -


[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.

Edited by student of Rachel Larsen and Kit Pogliano