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

Os genomas microbianos mudam ao longo do tempo devido ao ganho e à perda de genes.Dentro de uma espécie, múltiplas cepas herdam consistentemente um conjunto compartilhado de genes conhecido como genoma central.Por exemplo, estima-se que a espécie bacteriana X possua cerca de 5 famílias gênicas principais compartilhadas entre as cepas analisadas.Além disso, algumas cepas podem ganhar genes extras, muitas vezes por meio de transferência horizontal de genes.O pângenoma da espécie X é formado pelo conjunto completo de famílias genéticas centrais presentes nas cepas estudadas, além dos genes extras encontrados em muitas cepas.Em algumas espécies, o pangenoma se expande continuamente à medida que novos conjuntos de genes são adquiridos.Esses genes adquiridos podem ser neutros ou até prejudiciais, levando a deleções gênicas comuns em genomas microbianos, enquanto a seleção natural mantém genes benéficos.Portanto, todos os genes para a sobrevivência básica fazem parte do genoma central de uma espécie.

evolução do genoma microbiano

A evolução do genoma microbiano é um processo altamente dinâmico moldado pelo ganho e perda contínuo de genes entre espécies e linhagens. Essa flexibilidade genômica permite que microrganismos se adaptem rapidamente às pressões ambientais e interações com outros organismos. Central para entender essa diversidade é a distinção entre os genomas central e pan.O genoma central compreende os genes compartilhados por todas as cepas amostradas de uma espécie, representando funções essenciais necessárias para processos celulares fundamentais. Por exemplo, estima-se que Salmonella enterica contenha cerca de 2.800 genes centrais, embora esse número varie conforme as cepas analisadas. Em contraste, o pangenoma inclui todos os genes encontrados em todas as cepas, incorporando tanto genes centrais quanto específicos da cepa. Certos sorovares, como S. enterica Typhimurium, contribuem com genes únicos que expandem o pangenoma da espécie.A transferência horizontal de genes (HGT) é um dos principais motores da aquisição de genes, introduzindo novas características que permitem aos microrganismos resistir a antibióticos, ocupar novos nichos ou metabolizar novos substratos. No entanto, muitos genes adquiridos não oferecem benefício e podem ser removidos por deleções genômicas ou deriva genética, ajudando a manter genomas otimizados em muitas linhagens microbianas. Ao mesmo tempo, alguns microrganismos experimentam expansão gênica quando seus nichos ecológicos exigem capacidades metabólicas mais amplas.A genômica comparativa revelou que todos os genomas bacterianos e arqueicos compartilham um pequeno conjunto de aproximadamente 30 a 60 famílias genéticas universalmente conservadas. Esses genes codificam funções essenciais como replicação do DNA, transcrição, tradução e vias metabólicas básicas, refletindo profundas restrições evolutivas.Juntas, a aquisição, perda de genes e retenção seletiva ilustram como os genomas microbianos permanecem notavelmente adaptáveis e fundamentalmente limitados por requisitos biológicos essenciais.

Evolução do 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

JoVE Core

Microbiology

Microbiologia

Unit

Unidade

Microbial Evolution

Evolução Microbiana

KEY TERMS AND CONCEPTS

TERMOS E CONCEITOS-CHAVE

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

origin of cellular life

How Early Cells Got Their Start

Early cellular life began under the harsh conditions of early Earth, where simple chemicals could form more complex organic molecules. Experimental evidence supports the idea that RNA nucleotides, amino acids, and lipids could arise spontaneously in this environment. Volcanic activity, strong UV radiation, and an atmosphere with little or no free oxygen likely helped drive these reactions. Hydrothermal vents on the ocean floor are considered one likely setting for the first life forms. These...

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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