science

Pseudomonadota

Pseudomonadota 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 Pseudomonadota rather than just read about it. In short: Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. They include both pathogenic and free-living (non-parasitic) genera.

Key takeaways

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

Reference excerpt

Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. They include both pathogenic and free-living (non-parasitic) genera. The phylum comprises six classes: Acidithiobacillia, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Hydrogenophilia, and Zetaproteobacteria. Pseudomonadota are very diverse, with differences in morphology, metabolic processes, relevance to humans, and ecological influence.

Classification American microbiologist Carl Woese established this grouping in 1987, calling it informally the "purple bacteria and their relatives". The group was later formally named Proteobacteria after the Greek god Proteus, who was known to assume many forms. In 2021, the International Committee on Systematics of Prokaryotes designated the synonym Pseudomonadota as part of a move to rename several phyla. This renaming remains controversial among microbiologists, many of whom continue to use the name Proteobacteria, which has a lot of precedent in the literature. The phylum includes a wide variety of pathogenic genera, such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many others. Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation. Previously, the Pseudomonadota phylum included two additional classes, namely Deltaproteobacteria and Oligoflexia. However, further investigation into the phylogeny of these taxa through genomic marker analysis indicated their separation from the Pseudomonadota phylum. Deltaproteobacteria has been identified as a diverse taxonomic unit, leading to a proposal for its reclassification into distinct phyla: Desulfobacterota, Myxococcota, and Bdellovibrionota. The class Epsilonproteobacteria was additionally identified within the Pseudomonadota phylum. This class is characterized by its significance as chemolithotrophic primary producers and its metabolic prowess in deep-sea hydrothermal vent ecosystems. Noteworthy pathogenic genera within this class include Campylobacter, Helicobacter, and Arcobacter. Analysis of phylogenetic tree topology and genetic markers revealed the direct divergence of Epsilonproteobacteria from the Pseudomonadota phylum. Limited outgroup data and low bootstrap values support these discoveries. Despite further investigations, consensus has not been reached regarding the monophyletic nature of Epsilonproteobacteria within Proteobacteria, prompting researchers to propose its taxonomic separation from the phylum. The proposed reclassification of the name Epsilonproteobacteria is Epsilonbacteraeota, later revised to Campylobacterota in 2018.

Taxonomy The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI). The group Pseudomonadota is defined based on ribosomal RNA (rRNA) sequencing, and are divided into several subclasses. These subclasses were regarded as such for many years, but are now treated as various classes of the phylum. These classes are monophyletic. The genus Acidithiobacillus, part of the Gammaproteobacteria until it was transferred to class Acidithiobacillia in 2013, was previously regarded as paraphyletic to the Betaproteobacteria according to multigenome alignment studies. In 2017, the Betaproteobacteria was subject to major revisions and the class Hydrogenophilalia was created to contain the order Hydrogenophilales Pseudomonadota classes with validly published names include some prominent genera: e.g.:

Acidithiobacillia: Acidithiobacillus, Thermithiobacillus Alphaproteobacteria: Brucella, Rhizobium, Agrobacterium, Caulobacter, Rickettsia, Wolbachia, etc. Betaproteobacteria: Bordetella, Ralstonia, Neisseria, Nitrosomonas, etc. Gammaproteobacteria: Escherichia, Shigella, Salmonella, Yersinia, Buchnera, Haemophilus, Vibrio, Pseudomonas, Pasteurella, etc. Zetaproteobacteria: Mariprofundus

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Pseudomonadota

Start with the simplest possible case. Write down what Pseudomonadota 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 Pseudomonadota 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 Pseudomonadota 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 Pseudomonadota

In research: Pseudomonadota 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 Pseudomonadota 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: Pseudomonadota is common in secondary-school and first-year university syllabi. It links to neighbouring topics Bacteria phyla, Gram-negative bacteria, Pseudomonadota, so understanding it makes those chapters shorter.
In everyday life: Look for Pseudomonadota 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 Pseudomonadota in 20 minutes

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

Frequently asked questions

What is Pseudomonadota in simple terms?

Pseudomonadota (synonym "Proteobacteria") is a major phylum of gram-negative bacteria. They include both pathogenic and free-living (non-parasitic) genera.

Why does Pseudomonadota 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 Pseudomonadota?

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 Pseudomonadota.