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

I genomi microbici cambiano nel tempo attraverso l'acquisizione e la perdita di geni.All'interno di una specie, più ceppi ereditano costantemente un insieme condiviso di geni noto come genoma centrale.Ad esempio, si stima che la specie batterica X possieda circa 5 famiglie geniche principali condivise tra i ceppi analizzati.Inoltre, alcuni ceppi possono acquisire geni extra, spesso tramite trasferimento genico orizzontale.Il pangenoma della specie X è formato dall'intero insieme delle famiglie geniche principali presenti nei ceppi studiati, oltre ai geni aggiuntivi presenti in molti ceppi.In alcune specie, il pangenoma si espande continuamente man mano che si acquisiscono nuovi insiemi di geni.Questi geni acquisiti possono essere neutrali o addirittura dannosi, portando a delezioni geniche comuni nei genomi microbici, mentre la selezione naturale mantiene i geni benefici.Quindi, tutti i geni per la sopravvivenza di base fanno parte del genoma centrale di una specie.

evoluzione del genoma microbico

L'evoluzione del genoma microbico è un processo altamente dinamico, modellato da un continuo guadagno e perdita genica tra specie e ceppi. Questa flessibilità genomica permette ai microrganismi di adattarsi rapidamente alle pressioni ambientali e alle interazioni con altri organismi. Centrale per comprendere questa diversità è la distinzione tra genomi core e pan.Il genoma centrale comprende i geni condivisi da tutti i ceppi campionati di una specie, rappresentando funzioni essenziali necessarie per i processi cellulari fondamentali. Ad esempio, si stima che Salmonella enterica contenga circa 2.800 geni centrali, anche se questo numero varia in base ai ceppi analizzati. Al contrario, il pangenoma include ogni gene presente in tutti i ceppi, incorporando sia geni core che specifici per ceppo. Alcuni serovari, come S. enterica Typhimurium, contribuiscono con geni unici che espandono il pan-genoma della specie.Il trasferimento genico orizzontale (HGT) è un motore principale dell'acquisizione genica, introducendo nuovi tratti che permettono ai microbi di resistere agli antibiotici, occupare nuove nicchie o metabolizzare nuovi substrati. Tuttavia, molti geni acquisiti non offrono alcun beneficio e possono essere rimossi tramite delezioni genomiche o deriva genetica, aiutando a mantenere genomi snelli in molte linee microbiche. Allo stesso tempo, alcuni microbi sperimentano l'espansione genica quando le loro nicchie ecologiche richiedono capacità metaboliche più ampie.La genomica comparativa ha rivelato che tutti i genomi batterici e archei condividono un piccolo insieme di circa 30–60 famiglie geniche universalmente conservate. Questi geni codificano funzioni fondamentali come la replicazione del DNA, la trascrizione, la traduzione e le vie metaboliche di base, riflettendo profondi vincoli evolutivi.Insieme, acquisizione, perdita e ritenzione selettiva dei geni illustrano come i genomi microbici rimangano sia straordinariamente adattabili sia fondamentalmente vincolati da requisiti biologici essenziali.

Evoluzione del genoma microbico

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

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JoVE Core

Microbiology

Microbiologia

Unit

Unità

Microbial Evolution

Evoluzione microbica

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

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 Early Cells Got Their Start

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origin of photosynthesis

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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