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

Mikrobiyal genomlar, genlerin kazanımı ve kaybı yoluyla zamanla değişir.Bir tür içinde, birden fazla suş çekirdek genom olarak bilinen ortak bir gen setini tutarlı tutarlı şekilde miras alır.Örneğin, bakteri türü X'in, analiz edilen suşlar arasında yaklaşık 5 çekirdek gen ailesine sahip olduğu tahmin edilmiştir.Ayrıca, bazı suşlar genellikle yatay gen transferiyle ekstra gen kazanabilir.X türünün pangenomu, incelenen suşlarda bulunan tüm çekirdek gen aileleri seti ile birçok suşta bulunan ek genlerden oluşur.Bazı türlerde, pan-genom yeni gen setleri kazandıkça sürekli genişler.Bu edinilmiş genler nötr veya hatta zararlı olabilir; bu da mikrobiyal genomlarda yaygın olan gen silinmelerine yol açarken, doğal seçilim faydalı genleri korur.Yani, temel hayatta kalma genlerinin hepsi bir türün çekirdek genomunun parçasıdır.

mikrobiyal genomun evrimi

Mikrobiyal genom evrimi, türler ve suşlar arasında sürekli gen kazanımı ve kaybıyla şekillenen son derece dinamik bir süreçtir. Bu genomik esneklik, mikroorganizmaların çevresel baskılara ve diğer organizmalarla etkileşimlere hızla uyum sağlamasını sağlar. Bu çeşitliliği anlamanın merkezinde çekirdek ve pan genomlar arasındaki ayrım yer alır.Çekirdek genom, bir türün örneklenen tüm suşlarının paylaştığı genleri içerir ve temel hücresel süreçler için gerekli temel işlevleri temsil eder. Örneğin, Salmonella enterica'nın yaklaşık 2.800 çekirdek gen içerdiği tahmin edilmektedir, ancak bu sayı analiz edilen suşlara göre değişir. Buna karşılık, pan-genom tüm suşlarda bulunan her geni içerir ve hem çekirdek hem de suş spesifik genleri içermektedir. S. enterica Typhimurium gibi bazı serovarlar, türün pan-genomunu genişleten benzersiz genler sağlar.Yatay gen transferi (HGT), gen ediniminin önemli bir itici güçüdür ve mikropların antibiyotiklere direnmesini, yeni nişlere girmesini veya yeni substratları metabolize etmesini sağlayan yeni özellikler ortaya koymaktadır. Ancak, birçok edinilmiş gen fayda sağlamaz ve genomik silinme veya genetik sürüklenme yoluyla çıkarılabilir; bu da birçok mikrobiyal çizgide genomların sade kalmasına yardımcı olur. Aynı zamanda, bazı mikroplar ekolojik nişleri daha geniş metabolik yetenekler talep ettiğinde gen genleşmesi yaşar.Karşılaştırmalı genomik, tüm bakteriyel ve arkeal genomların yaklaşık 30–60 evrensel korunan gen ailesinden oluşan küçük bir seti paylaştığını ortaya koymuştur. Bu genler, DNA replikasyonu, transkripsiyon, çeviri ve temel metabolik yollar gibi temel işlevleri kodlar; bu da derin evrimsel kısıtlamaları yansıtır.Gen edinimi, kaybı ve seçici tutulma birlikte, mikrobiyal genomların hem olağanüstü uyum sağlayabildiğini hem de temel biyolojik gereksinimlerle temelde kısıtlandığını gösterir.

Mikrobiyal Genomun Evrimi

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

https://cloudfront.jove.com/files/ftp_upload/40723/40723_article_thumb_40723.jpg

Education

JoVE Core

Microbiology

Mikrobiyoloji

Unit

Birim

Microbial Evolution

Mikrobiyal Evrim

KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

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

Description

Transcript

Tags