science

Propionigenium modestum

Propionigenium modestum is a science 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 Propionigenium modestum rather than just read about it. In short: Propionigenium modestum is a species of gram-negative, strictly anaerobic bacteria. It is rod-shaped and around 0.5-0.6 x 0.5-2.0μm in size.

Key takeaways

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

Reference excerpt

Propionigenium modestum is a species of gram-negative, strictly anaerobic bacteria. It is rod-shaped and around 0.5-0.6 x 0.5-2.0μm in size. It is important in the elucidation of mechanism of ATP synthase.

Etymology The word propionigenium comes from the Latin word acidum propionicum meaning propionic acid and genre is Latin for make or produce. Modestus comes from the Latin word meaning modest, referring to an extremely modest type of metabolism.

Taxonomic Information Propionigenium modestum's current classification is Bacteria, Fusobacteria, Fusobacteria, Fusobacteriales, Fusobacteriaceae, Propionigenium, Modestum. Propionigenium modestum and Propionigenium maris, currently, are the only two species belonging to the genus Propionigenium. They both inhabit marine environments. P. modestum was found to be more closely related to Ilyobacter insuetus than it is to P. maris. P. modestum and I. insuetus share 97±4 - 98±5% 16S rRNA (ribosomal Ribonucleic Acid), while P. modestum and P. maris only share 96±5 - 96±8%. Only two species in the family Fusobacteriaceae have had their entire genomes sequenced; one being llyobacter polytropus.

Discovery P. modestum was isolated by Bernhard Schink and Norbert Pfenning in 1982. It was first isolated from black, anaerobic mud from Canale Grande in Venice, Italy, and was later isolated from human saliva. The original isolation of P. modestum was obtained through a succinate media, which was used as the primary source of energy. It was reported that for every mol of succinate that was fermented by P. modesetum, there was between 2.1 and 2.4 grams of cell dry weight isolated from the media.

Characteristics P. modestum is a non-sporing and non-motile bacteria. Its growth optimum is pH of 7.1-7.7 and a temperature of 33 °C. The G+C content is 33.9%. It utilizes succinate, fumarate, malate, aspartate, oxaloacetate, and pyruvate for growth and fermentes them to propionate, (acetate), and carbon dioxide (CO2). This organism grows optimally in fresh and saltwater, as well as human saliva under anaerobic conditions. Propionigenium modestum converts succinate (as well as other energy sources) to propionate to generate energy. The conversion has a small free energy change so there is no electron-transport chain or substrate-linked phosphorylation.

Importance F-type ATPases (Adenylpyrophosphatase ) typically use protons as the sole coupling ion, but the F1F0 ATPase of Propionigenium modestum is the first discovered which uses sodium ions (Na+). The discovery of the ATPase in P. modestum is important because it demonstrated that the chemiosmosis theory as proposed by Peter D. Mitchell was incorrect. Mitchell proposed that the H+ was consumed in the synthesis of ATP by reacting directly with O2 converting it to H2O while producing ATP from ADP. Instead the F-type ATPase of P. modestum uses only Na+ to drive the reaction, demonstrating the production of H2O from O2 during the synthesis of ATP does not consume the H+ used by all other known F-type ATPases. Thus demonstrating that it is the H+ gradient that drives ATP synthase.

Activity The ATPase of P. modestum acts about 6 times higher than bacterial membranes, at 6.6 units/mg of protein. The ATPase is composed of subunits a, b, and c. It has been found that subunit c is extremely stable and does not dissociate during SDS (Sodium Dodecyl Sulfate) gel electrophoresis until 120 °C.

References

mitchell febs lett 43 189

Further reading P. Dimroth (July 1992). "The ATPases of Propionigenium modestum and Bacillus alcalophilus. Strategies for ATP synthesis under low energy conditions". Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1101 (2): 236–239. doi:10.1016/0005-2728(92)90234-s. PMID 1385980. Laubinger, Werner; Dimroth, Peter (1989). "The sodium ion translocating adenosine triphosphatase of Propionigenium modestum pumps protons at low sodium ion concentrations". Biochemistry. 28 (18): 7194–7198. doi:10.1021/bi00444a010. ISSN 0006-2960. PMID 2554965. Dimroth, P.; Wang, H.; Grabe, M.; Oster, G. (1999). "Energy transduction in the sodium F-ATPase of Propionigenium modestum". Proceedings of the National Academy of Sciences. 96 (9): 4924–4929. Bibcode:1999PNAS...96.4924D. doi:10.1073/pnas.96.9.4924. ISSN 0027-8424. PMC 21793. PMID 10220395.

External links J.P. Euzéby: List of Prokaryotic names with Standing in Nomenclature "Propionigenium modestum". The Encyclopedia of Life. Type strain of Propionigenium modestum at BacDive - the Bacterial Diversity Metadatabase

Worked examples

Example 1 — a first encounter with Propionigenium modestum

Start with the simplest possible case. Write down what Propionigenium modestum claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Propionigenium modestum 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 Propionigenium modestum 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 Propionigenium modestum

In research: Propionigenium modestum appears in science 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 Propionigenium modestum 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: Propionigenium modestum is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacteria described in 1983, Fusobacteriota, so understanding it makes those chapters shorter.
In everyday life: Look for Propionigenium modestum 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.

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How to study Propionigenium modestum in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Propionigenium modestum 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 Propionigenium modestum out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Propionigenium modestum in simple terms?

Propionigenium modestum is a species of gram-negative, strictly anaerobic bacteria. It is rod-shaped and around 0.5-0.6 x 0.5-2.0μm in size.

Why does Propionigenium modestum matter?

Because it connects several science 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 Propionigenium modestum?

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 Propionigenium modestum.