biology

Shewanella violacea

Shewanella violacea is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Shewanella violacea rather than just read about it. In short: Shewanella violacea DSS12 (S. violacea) is a gram-negative bacterium located in marine sediment in the Ryukyu Trench at a depth of 5,110m. The first description of this organism was published in 1998 by Japanese microbiologists Yuichi Nogi, Chiaki Kato, and Koki Horikoshi, who named the species after its violet appearance when it is grown on Marine Agar 2216 Plates.

Key takeaways

Shewanella violacea belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Shewanella violacea to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Shewanella violacea from memory before moving on to harder problems.

Reference excerpt

Shewanella violacea DSS12 (S. violacea) is a gram-negative bacterium located in marine sediment in the Ryukyu Trench at a depth of 5,110m. The first description of this organism was published in 1998 by Japanese microbiologists Yuichi Nogi, Chiaki Kato, and Koki Horikoshi, who named the species after its violet appearance when it is grown on Marine Agar 2216 Plates. Shewanella violacea is a motile rod-shaped bacterium with flagella. It is a facultative anaerobic organism and considered an extremophile due to its optimal growing conditions at 8°C and 30 MPa. Researchers are evaluating this species to better understand the specific mechanisms S. violacea uses in order to thrive in its unusually cold and high-pressure environment.

Taxonomy Shewanella violacea is a member of the Shewanella genus. Recent evaluation of the Shewanella phylogeny has led to a division of this genus into two categories: Group 1 and Group 2. These categories were created from an evaluation of the 16S rRNA sequences as well as a comparison of membrane lipid compositions. Group 1 Shewanella species are mostly extremophiles while Group 2 Shewanella species are mostly mesophiles. S. violacea is a member of Group 1 Shewanella due to specific genetic adaptations that have enabled the bacteria to thrive in extremely low temperatures and high pressures. Specifically, Group 1 species contain a notably higher percentage of polyunsaturated fatty acids integrated in their membranes.

Location Samples of S. violacea have been collected using the SHINKAI 6500 System, a crewed submersible operated by the Japan Marine Science and Technology Center. Samples have been collected from the Ryukyu Trench at a depth of 5,110 m. The bacteria are found in the topmost layer of the sediment in this marine environment.

Structure and metabolism

Genome The complete genome of S. violacea was successfully sequenced in 2010 using the Sanger method. S. violacea contains 4,962,103 base pairs. It has 4,346 protein genes and 169 RNA genes. The bacterium contains a single chromosome and no known plasmids. The G+C content is 44.7%. The complete genome is accessible online as published by the National Center for Biotechnology Information (see external links).

Membrane composition Shewanella violacea has an abnormally high percent of polyunsaturated fatty acids (PUFA) integrated into its phospholipids. In Shewanella violacea 14% of its fatty acids are eicosapentaenoic acids (EPA) which are a specific type of polyunsaturated fatty acid also known as 20:5ω3. Increased PUFA concentrations decrease the membrane fluidity and help the bacterium thrive in the cold temperatures. The exact function of the unusual lipid composition found in S. violacea and other members of Group 1 Shewanella species is not yet fully understood. Nevertheless, high EPA levels in S. violacea have been correlated with greater rates of cell division in high pressures as well as in low temperatures.

Ideal growth conditions Shewanella violacea is an obligate psychrophile (cryophile). Its optimum growth temperature is 8°C. It is not able to grow or reproduce at 30°C. S. violacea is a facultative piezophile (barophile) which means that it is able to thrive in high pressure conditions. S. violacea is able to grow in pressure conditions ranging from 0.1 to 70 MPa (3). Its ideal pressure is 30 MPa.

Maintenance of respiratory system at high pressures Unlike many other Shewanella species, S. violacea has very few terminal reductases for anaerobic respiration, c-type cytochromes and no Fe(III) reduction outer membrane proteins involved in respiration. A pressure related operon is believed to play an integral role in the regulation of the respiratory system in S. violacea. Specifically, researchers are evaluating the significance of pressure regulated cytochromes. Cytochromes are hemeproteins involved in the generation of ATP via electron transport. S. violacea contains three main types of cytochromes. The first, CA is expressed at all viable pressures. The second, CB, is only expressed at low pressures. The third, a d-type cytochrome is expressed only when the cells are grown under high pressure. The d-type cytochrome in S. violacea is thus a critical means for the respiratory system to remain active at high pressures.

References

External links Complete S. violacea genome at National Center for Biotechnology Information (NCBI) Type strain of Shewanella violacea at BacDive - the Bacterial Diversity Metadatabase

Worked examples

Example 1 — a first encounter with Shewanella violacea

Start with the simplest possible case. Write down what Shewanella violacea claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Shewanella violacea before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Shewanella violacea ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Shewanella violacea

In research: Shewanella violacea appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Shewanella violacea in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Shewanella violacea is common in secondary-school and first-year university syllabi. It links to neighbouring topics Alteromonadales, Bacteria described in 1999, Gram-negative bacteria, so understanding it makes those chapters shorter.
In everyday life: Look for Shewanella violacea outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Shewanella violacea” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Shewanella violacea in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Shewanella violacea means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Shewanella violacea out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shewanella violacea in simple terms?

Why does Shewanella violacea matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Shewanella violacea?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Shewanella violacea.