Name: microbial core and pan-genome changes
Uploaded: 2026-03-12T13:57:40.000Z
Duration: 1 min 8 s
Channel: JoVE

Mikrobielle Genome verändern sich im Laufe der Zeit durch den Gewinn und Verlust von Genen.Innerhalb einer Art erben mehrere Stämme konsequent einen gemeinsamen Satz von Genen, bekannt als das Kerngenom.Zum Beispiel wird geschätzt, dass die Bakterienart X etwa 5 Kerngenfamilien besitzt, die über die analysierten Stämme hinweg geteilt werden.Außerdem können einige Stämme zusätzliche Gene erhalten, oft durch horizontalen Gentransfer.Das Pangenom von Spezies X besteht aus dem vollständigen Satz der Kerngenfamilien, die in den untersuchten Stämmen vorkommen, plus den zusätzlichen Genen, die bei vielen Stämmen vorkommen.Bei einigen Arten erweitert sich das Pangenom kontinuierlich, wenn neue Gensätze gewonnen werden.Diese erworbenen Gene können neutral oder sogar schädlich sein, was zu Gen-Deletionen führt, die in mikrobiellen Genomen häufig vorkommen, während die natürliche Selektion nützliche Gene behält.Alle Gene für das grundlegende Überleben sind also Teil des Kerngenoms einer Spezies.

evolution des mikrobiellen genoms

Die mikrobielle Genomevolution ist ein hochdynamischer Prozess, der durch kontinuierlichen Genzuwachs und -verlust zwischen Arten und Stämmen geprägt ist. Diese genomische Flexibilität ermöglicht es Mikroorganismen, sich schnell an Umweltbelastungen und Wechselwirkungen mit anderen Organismen anzupassen. Zentral für das Verständnis dieser Vielfalt ist die Unterscheidung zwischen dem Kern- und dem Pangenom.Das Kerngenom besteht aus den Genen, die von allen beprobten Stämmen einer Art geteilt werden und wesentliche Funktionen darstellen, die für grundlegende zelluläre Prozesse erforderlich sind. Zum Beispiel wird geschätzt, dass Salmonella enterica etwa 2.800 Kerngene enthält, wobei diese Zahl je nach analysierten Stämmen variiert. Im Gegensatz dazu umfasst das Pangenom jedes Gen, das in allen Stämmen vorkommt, und umfasst sowohl kernspezifische als auch stammspezifische Gene. Bestimmte Serovars, wie S. enterica Typhimurium, tragen einzigartige Gene bei, die das Pangenom der Art erweitern.Horizontaler Gentransfer (HGT) ist ein wesentlicher Treiber der Genaufnahme, da er neue Eigenschaften einführt, die es Mikroben ermöglichen, Antibiotikaresistenz zu leisten, neue Nischen zu besetzen oder neuartige Substrate zu metabolisieren. Viele erworbene Gene bieten jedoch keinen Nutzen und können durch genomische Deletionen oder genetische Drift entfernt werden, was dazu beiträgt, in vielen mikrobiellen Linien eine optimierte Genomstruktur zu erhalten. Gleichzeitig erleben einige Mikroben eine Generweiterung, wenn ihre ökologischen Nischen breitere metabolische Fähigkeiten erfordern.Die vergleichende Genomik hat gezeigt, dass alle bakteriellen und archäalen Genome einen kleinen Satz von etwa 30–60 universell konservierten Genfamilien teilen. Diese Gene codieren für Kernfunktionen wie DNA-Replikation, Transkription, Translation und grundlegende Stoffwechselwege, was tiefgreifende evolutionäre Einschränkungen widerspiegelt.Zusammen zeigen Generwerbung, -verlust und selektive Erhaltung, wie mikrobielle Genome sowohl bemerkenswert anpassungsfähig als auch grundlegend durch wesentliche biologische Anforderungen eingeschränkt bleiben.

Evolution des mikrobiellen Genoms

Microbial genome evolution is a highly dynamic process shaped by continual gene gain and loss across species and strains. This genomic flexibility allows ...

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Education

Lehre

JoVE Core

Microbiology

Mikrobiologie

Unit

Einheit

Microbial Evolution

Mikrobielle Evolution

KEY TERMS AND CONCEPTS

SCHLÜSSELBEGRIFFE UND KONZEPTE

Evolution of Microbial Genome

microbial core and pan-genome changes

Microbial genomes change through gene gain and gene loss. These changes help microbes adapt to new environments and to other organisms they live with. In many species, genome evolution is fast and ongoing.

A key idea is the difference between the core genome and the pan-genome. The core genome is the set of genes shared by all sampled strains of a species. These genes support basic cell functions. For example, Salmonella enterica has about 2,800 core genes, although the exact number can change with the strains studied.

The pan-genome includes every gene found across all strains of a species. It contains both the core genes and genes found only in certain strains. In Salmonella enterica, strains such as S. enterica Typhimurium add unique genes that expand the pan-genome.

Horizontal gene transfer, or HGT, is a major way microbes gain new genes. It can give them traits that help them resist antibiotics, use new nutrients, or live in new habitats. Some acquired genes are not useful and may later be removed by genome deletions or genetic drift, which helps keep many microbial genomes streamlined. In some niches, however, microbes expand their gene sets when they need wider metabolic abilities.

Comparative genomics has also shown that bacterial and archaeal genomes share a small group of about 30 to 60 gene families. These conserved genes carry out DNA replication, transcription, translation, and core metabolism. Together, gene acquisition, gene loss, and selective retention show how microbial genomes stay flexible while still keeping essential biological functions.

Microbial Core and Pan-Genome Changes

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How Photosynthesis Changed Earth

Photosynthesis changed Earth’s atmosphere and made complex life possible. It began about 3.4 to 3.8 billion years ago, when the first photosynthetic organisms used light energy to build organic compounds. These early organisms were anoxygenic phototrophs, which means they made food from light but did not release oxygen. Early photosynthesis used hydrogen sulfide (H2S) or ferrous iron (Fe2+) as electron donors instead of water. Because of that, it did not produce molecular oxygen (O2) as a...

evolutionary processes in microbes

How Microbes Gain New Traits

Microbes gain new traits through fast genetic change. Their short generation times help evolution happen quickly. Mutation, horizontal gene transfer, recombination, and genetic drift all contribute to this process. Together, these mechanisms help microbial populations adjust to changing environments. Horizontal gene transfer, or HGT, moves genes between different species. It happens in three main ways: conjugation, transformation, and transduction. Conjugation requires direct cell-to-cell...

evolution of new traits in microbes

Microbial Adaptation in Changing Environments

Microbial adaptation in changing environments can happen very quickly. Microorganisms often evolve fast because they have large population sizes and short generation times. In the lab, these changes can sometimes be measured within days. Natural selection acts on standing genetic variation, which is the genetic diversity already present in a population. When conditions change, helpful traits can be kept and increased because they improve fitness. This lets microbes respond to new pressures...

evolution of microbial genome

Microbial genomes change through gene gain and gene loss. These changes help microbes adapt to new environments and to other organisms they live with. In many species, genome evolution is fast and ongoing. A key idea is the difference between the core genome and the pan-genome. The core genome is the set of genes shared by all sampled strains of a species. These genes support basic cell functions. For example, Salmonella enterica has about 2,800 core genes, although the exact number can change...

microbial phylogeny

Reading Microbial Family Trees

Reading microbial family trees helps scientists study how microorganisms are related. These trees are important in microbial ecology and taxonomy. They use molecular sequences such as DNA, RNA, or proteins to compare bacteria and archaea and trace genetic changes over time. A phylogenetic tree has tips, branches, and nodes. The tips are the species that are sampled or still alive. The branches show evolutionary paths, and branch length reflects the number of genetic changes between nodes.

phylogenetic species concept in microbiology

phylogenetic-species-concept-in-microbiology

How DNA Defines Microbial Species

The phylogenetic species concept helps define microbial species by looking at DNA and evolutionary relatedness. It focuses on shared ancestry and genetic traits that can be diagnosed in different organisms. This approach is especially useful in microbiology, where other species concepts often do not work well. Traditional morphological and biological species concepts rely on body form or reproduction. Those methods can fall short for microbes because many reproduce asexually, show little...

key terms and concepts

Learn how microbial genomes change through gene gain, gene loss, HGT, core genes, and pan-genomes using Salmonella enterica as an example.

Microbial Core and Pan-Genome Changes | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Microbial Core and Pan-Genome Changes

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