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

Los genomas microbianos cambian con el tiempo a través de la ganancia y pérdida de genes.Dentro de una especie, múltiples cepas heredan consistentemente un conjunto compartido de genes conocidos como el genoma central.Por ejemplo, se estima que la especie bacteriana X posee alrededor de 5 familias génicas principales compartidas entre las cepas analizadas.Además, algunas cepas pueden adquirir genes adicionales, a menudo mediante transferencia horizontal de genes.El pangenoma de la especie X está formado por el conjunto completo de familias génicas centrales presentes en las cepas estudiadas, además de los genes adicionales que se encuentran en muchas cepas.En algunas especies, el pangenoma se expande continuamente a medida que se adquieren nuevos conjuntos de genes.Estos genes adquiridos pueden ser neutrales o incluso dañinos, lo que conduce a deleciones génicas comunes en los genomas microbianos, mientras que la selección natural conserva genes beneficiosos.Así que, todos los genes básicos para la supervivencia forman parte del genoma central de una especie.

evolución del genoma microbiano

La evolución del genoma microbiano es un proceso altamente dinámico moldeado por la ganancia y pérdida continua de genes entre especies y cepas. Esta flexibilidad genómica permite que los microorganismos se adapten rápidamente a las presiones ambientales e interacciones con otros organismos. Fundamental para entender esta diversidad es la distinción entre el genoma núcleo y el genoma de Pan.El genoma central comprende los genes compartidos por todas las cepas muestreadas de una especie, representando funciones esenciales necesarias para los procesos celulares fundamentales. Por ejemplo, se estima que Salmonella enterica contiene aproximadamente 2.800 genes centrales, aunque este número varía según las cepas analizadas. En cambio, el pangenoma incluye todos los genes encontrados en todas las cepas, incorporando tanto genes centrales como específicos de la cepa. Ciertos serovares, como S. enterica Typhimurium, contribuyen con genes únicos que amplían el pangenoma de la especie.La transferencia horizontal de genes (HGT) es un factor clave en la adquisición de genes, introduciendo nuevos rasgos que permiten a los microbios resistir los antibióticos, ocupar nuevos nichos o metabolizar sustratos novedosos. Sin embargo, muchos genes adquiridos no ofrecen ningún beneficio y pueden eliminarse mediante deleciones genómicas o deriva genética, ayudando a mantener genomas optimizados en muchas líneas microbianas. Al mismo tiempo, algunos microbios experimentan expansión génica cuando sus nichos ecológicos requieren capacidades metabólicas más amplias.La genómica comparativa ha revelado que todos los genomas bacterianos y arqueos comparten un pequeño conjunto de aproximadamente 30–60 familias génicas universalmente conservadas. Estos genes codifican funciones fundamentales como la replicación del ADN, la transcripción, la traducción y las vías metabólicas básicas, reflejando profundas limitaciones evolutivas.En conjunto, la adquisición, pérdida y retención selectiva de genes ilustran cómo los genomas microbianos siguen siendo notablemente adaptables y fundamentalmente limitados por requisitos biológicos esenciales.

Evolución del genoma microbiano

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

Educación

JoVE Core

Microbiology

Microbiología

Unit

Unidad

Microbial Evolution

Evolución microbiana

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

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...

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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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