science

Roseiflexus castenholzii

Roseiflexus castenholzii 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 Roseiflexus castenholzii rather than just read about it. In short: Roseiflexus castenholzii is a heterotrophic, thermophilic, filamentous anoxygenetic phototroph (FAP) bacterium. This species is in one of two genera of FAPs that lack chlorosomes.

Key takeaways

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

Reference excerpt

Roseiflexus castenholzii is a heterotrophic, thermophilic, filamentous anoxygenetic phototroph (FAP) bacterium. This species is in one of two genera of FAPs that lack chlorosomes. R. castenholzii was first isolated from red-colored bacterial mats located Nakabusa hot springs in Japan. Because this organism is a phototroph, it utilizes photosynthesis to fix carbon dioxide and build biomolecules. R. castenholzii has three photosynthetic complexes: light-harvesting only, reaction center only, and light-harvesting with reaction center.

Morphology This bacterium has a cell diameter is of 0.8–1.0 micrometers but does not have a definite length because of its multicellular filamentous structure. The bacterium is red to reddish-brown forms distinct red bacterial mats in the natural environment. R. castenholzii lacks internal vesicles, internal membranes, and complex structures. This species has gliding motility.

Phylogeny The five currently known genera of FAP organisms are Chloroflexus, Choronema, Oscillochloris, Roseiflexus, and Heliothrix. Of these five, only two do not contain chlorosomes: Roseiflexus and Heliothrix. Roseiflexus and Heliothrix are both red due to only having Bchl a as a photosynthetic pigment. In most other aspects, both phenotypically and genetically, the genera Roseiflexus and Heliothrix are different from each other. Little is known about the taxonomy of the Roseiflexus genus due to it only containing one known species: Roseiflexus casternholzii.

Habitat When first discovered, Roseiflexus castenholzii was isolated from the lowest layer of a three layered bacterial mat; the top two layers contained cyanobacteria and Chloroflexus spp. These mats were found in multiple Japanese hot springs ranging in temperature from 45.5 °C to 68.5 °C and with a neutral to alkaline pH range. This bacterium is able to grow photoheterotrophically under anaerobic light conditions and chemoheterotrophically under aerobic dark conditions. Optimal growth conditions for this organism are 50 °C and pH 7.5–8.0. The first isolated type strain was HLO8T (= DSM 13941T = JCM 11240T).

Photosynthesis In order to conduct photosynthesis, Roseiflexus castenholzii contains three different complexes: light-harvesting only (LH), reaction center only (RC) and light-harvesting with reaction center (LHRC). In contrast to most other FAPs, R. castenholzii does not have chlorosomes, which contain great amounts of photosynthetic pigments. Because chlorosomes can obstruct observations of photosynthetic complexes, Roseiflexus castenholzii is considered a model organism to study the reaction centers FAPs have. The LHRC contains both light harvesting and reaction center peptides that allow for absorbing light and exciting electrons in one complex. The light-harvesting complex contains antenna pigments that allow the bacterium to absorb light around 800 nanometers. The majority of these pigments are bacteriochlorophyll (BChl). The reaction center in Roseiflexus castenholzii is closely related to the RC of Chloroflexus aurantiacus. R. castenholzii's RC complex contains three subunits: L, M, and a c-type cytochrome. It lacks the H subunit common in purple bacteria. The RC also contains BChl and bacteriopheophytin (BPhe) pigments.

References

Worked examples

Example 1 — a first encounter with Roseiflexus castenholzii

Start with the simplest possible case. Write down what Roseiflexus castenholzii 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 Roseiflexus castenholzii 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 Roseiflexus castenholzii 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 Roseiflexus castenholzii

In research: Roseiflexus castenholzii 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 Roseiflexus castenholzii 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: Roseiflexus castenholzii is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacteria described in 2002, Chloroflexota, Thermophiles, so understanding it makes those chapters shorter.
In everyday life: Look for Roseiflexus castenholzii 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 Roseiflexus castenholzii in 20 minutes

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

Frequently asked questions

What is Roseiflexus castenholzii in simple terms?

Roseiflexus castenholzii is a heterotrophic, thermophilic, filamentous anoxygenetic phototroph (FAP) bacterium. This species is in one of two genera of FAPs that lack chlorosomes.

Why does Roseiflexus castenholzii 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 Roseiflexus castenholzii?

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 Roseiflexus castenholzii.