Name: microbial adaptation in changing environments
Uploaded: 2026-03-12T13:57:34.000Z
Duration: 1 min 24 s
Channel: JoVE

미생물은 짧은 세대 시간과 큰 개체군 규모 때문에 빠르게 진화하여 실험실에서 진화를 연구하기에 이상적입니다.자연선택은 집단 내 기존 대립유전자 변이에 작용하여, 변화하는 환경에서 유용한 변이체를 가진 집단이 더 풍부하게 작용합니다.예를 들어, 혐기성 조건에서 Rhodobacter은 박테리오클로로필과 카로티노이드 색소를 이용해 빛을 이용해 광합성을 수행합니다.장기간 어둠 속에서는 로도박터 색소가 거의 효과를 내지 못해 개체군 내 색소가 부족한 돌연변이체를 선호합니다. 하지만 빛이 돌아오면 야생형이 우세해집니다.또 다른 예는 진행 중인 '장기 진화 실험'입니다. 1988년에 12개의 동일한 대 장균 개체군이 포도당 제한 환경에서 자라는 상태로 시작되었습니다.그 이후로 이 실험은 8만 세대가 넘는 시기를 추적해왔습니다.시간이 지나면서 한 대 장균 집단은 희귀 돌연변이를 얻었다. 그리고 이 집단은 산소가 풍부한 환경에서 시트레이트를 대사할 수 있게 해주었습니다.이 돌연변이는 새로운 영양소에 접근할 수 있게 해주었고, 조상들에 대한 경쟁 우위를 제공했습니다.

미생물 내 새로운 형질의 진화

미생물은 개체군 규모가 크고 세대 시간이 짧아 빠르게 진화하며, 실험실 조건에서 며칠 내에 측정 가능한 변화를 보이기도 합니다. 자연선택은 기존 유전적 변이에 작용하여 변화하는 환경에서 적합도를 높이는 유익한 형질을 보존하고 증폭시킬 수 있게 합니다.<h3> 로도박터의 적응적 색소 조절</h3>보라색 비황 박테리아 속인 로도박테르에서는 박테리오클로로필과 카로티노이드와 같은 빛 수집 색소가 혐기성 조명 조건에서 광합성을 가능하게 합니다. 이 색소들의 발현은 환경 산소와 빛의 수준에 의해 광합성 활동에 맞춰 엄격히 조절됩니다.하지만 어둠 속에서는 안료가 기능적 이점을 제공하지 않고 오히려 에너지적 부담을 줍니다. 그 결과, 이러한 색소가 없는 돌연변이가 발생하며, 대사 비용이 줄어 어두운 환경에서 선호됩니다. 그럼에도 불구하고, 빛이 다시 나타날 때는 이 색소 결핍 돌연변이들이 광합성이 가능한 야생형 세포에 의해 경쟁에서 밀립니다.이러한 가역적 선택 패턴은 환경 변동이 대사 효율과 에너지 획득 사이의 균형을 변화시키는 적응적 상충관계를 보여줍니다.<h3>대장균의 장기 진화 실험 </h3>미생물 진화의 또 다른 대표적인 예는 1988년 리처드 렌스키가 시작한 장기 진화 실험(LTEE)입니다. 이 진행 중인 연구는 8만 세대 이상 포도당 제한 배지에서 배양된 대장균 집단을 추적해 왔습니다. 시간이 흐르면서 이 계통들은 세포 크기 증가, 성장 속도 증가, 대사 경로 최적화 등 다양한 적응을 진화시켜 왔습니다.<h3>시트레이트 이용의 진화</h3>특히 한 계통은 호기성 조건에서 시트레이트를 대사할 수 있는 능력을 진화시켰는데, 이는 산소가 있는 상태에서 시트레이트를 수입할 수 없는 야생형 대장균에는 일반적으로 없는 특성입니다. 이 혁신은 돌연변이 균주가 접근하기 어려운 자원을 이용해 상당한 선택적 이점을 얻게 했습니다.유전학적 분석 결과, 이 형질은 일련의 돌연변이를 통해 발생했음이 밝혀졌는데, 처음에는 시트레이트 이용(증강)의 잠재력을 확립한 뒤, 실제 발현과 운송(실현)을 가능하게 하는 돌연변이가 이어졌다. 이 발견은 진화 혁신에서 우발성, 돌연변이, 자연선택이 상호작용한다는 점을 강조합니다.이 연구들은 미생물 시스템이 진화 과정을 실시간으로 관찰하는 역동적 모델로서 어떻게 작동하는지를 보여줍니다. 이들은 생물학적 다양성과 혁신을 이끄는 결정론적 힘과 확률적 사건들을 모두 보여줍니다.

Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under ...

https://cloudfront.jove.com/files/ftp_upload/40722/40722_article_thumb_40722.jpg

Education

교육

JoVE Core

Microbiology

미생물학

Unit

단위

Microbial Evolution

미생물 진화

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 without waiting for brand-new mutations.

One example is Rhodobacter, a group of purple non-sulfur bacteria. These cells use light-harvesting pigments such as bacteriochlorophyll and carotenoids to support photosynthesis when oxygen is low and light is available. Their pigment production is tightly controlled by oxygen and light levels.

In darkness, those pigments no longer help the cells. They also cost energy to make and maintain. Because of that cost, mutants that lose the pigments can be favored in the dark. When light returns, wild-type cells that can photosynthesize again outcompete the pigment-deficient mutants. This is a reversible selection pattern that shows a trade-off between saving energy and capturing light.

A second major example is the Long-Term Evolution Experiment, or LTEE, started by Richard Lenski in 1988. The study has followed Escherichia coli grown in a glucose-limited medium for more than 80,000 generations. Over time, these lineages evolved changes such as larger cell size, faster growth, and better metabolic pathways.

The best-known LTEE result is one lineage that gained the ability to use citrate under aerobic conditions. Wild-type E. coli usually cannot import citrate when oxygen is present, so this trait opened access to a new food source. Genetic analysis showed that the trait appeared through a series of mutations. First came potentiation, which created the potential for citrate use. Then later mutations enabled actualization, or the real expression and transport of citrate.

Together, these microbial studies show evolution in real time. They highlight how mutation, natural selection, chance, and environmental change can work together to create new traits and shape biological diversity.

Microbial Adaptation in Changing Environments

microbial-adaptation-in-changing-environments

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 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 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...

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

See how microbes adapt through natural selection, pigment changes in Rhodobacter, and the E. coli LTEE, including the evolution of citrate use.

Microbial Adaptation in Changing Environments | 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 Adaptation in Changing Environments

Description

Transcript

Tags