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

Los microbios evolucionan rápidamente debido a tiempos de generación cortos y grandes tamaños poblacionales, lo que los hace ideales para estudiar la evolución en laboratorio.La selección natural actúa sobre las variantes aleladas existentes en la población, haciendo que los grupos con variantes útiles sean más abundantes en entornos cambiantes.Por ejemplo, en condiciones anaeróbicas, Rhodobacter utiliza la luz para realizar la fotosíntesis, utilizando los pigmentos bacterioclorofila y carotenoides.Durante la oscuridad prolongada, los pigmentos de Rhodobacter tienen poco beneficio, favoreciendo a los mutantes sin pigmento en la población. Pero el tipo salvaje domina cuando vuelve la luz.Otro ejemplo es el experimento en curso llamado 'Experimento de Evolución a Largo Plazo'. Se inició en 1988 con 12 poblaciones idénticas de E. coli creciendo en un entorno con baja glucosa.Desde entonces, este experimento ha seguido más de 80.000 generaciones.Con el tiempo, una población de E. coli adquirió una mutación rara. Y permitió que esta población metabolizara el citrato en condiciones ricas en oxígeno.Esta mutación les proporcionó acceso a una nueva fuente de nutrientes y una ventaja competitiva sobre sus antepasados.

evolución de nuevos rasgos en microbios

Los microorganismos evolucionan rápidamente debido a sus grandes tamaños poblacionales y a los cortos tiempos de generación, mostrando a menudo cambios medibles en cuestión de días bajo condiciones de laboratorio. La selección natural actúa sobre la variación genética permanente, permitiendo la retención y amplificación de rasgos beneficiosos que confieren ventajas de aptitud en entornos cambiantes.<h3>Regulación adaptativa del pigmento en los Rhodobacter</h3>En Rhodobacter, un género de bacterias púrpuras no sulfurosas, pigmentos que captan la luz como la bacterioclorofila y los carotenoides permiten la fotosíntesis bajo condiciones anaeróbias e iluminadas. La expresión de estos pigmentos está estrictamente regulada por el osígeno ambiental y los niveles de luz para alinearse con la actividad fotosintética.Sin embargo, en la oscuridad, los pigmentos no ofrecen ningún beneficio funcional y en cambio imponen una carga energética. Como resultado, surgen mutantes que carecen de estos pigmentos y son favorecidos en condiciones oscuras debido a la reducción de los costes metabólicos. Sin embargo, cuando la luz vuelve a estar disponible, estos mutantes deficientes en pigmento son superados por células salvajes capaces de fotosíntesis.Este patrón de selección reversible muestra un compromiso adaptativo, donde las fluctuaciones ambientales desplazan el equilibrio entre eficiencia metabólica y adquisición de energía.<h3>Experimento de evolución a largo plazo en E. coli</h3>Otro ejemplo emblemático de evolución microbiana es el Experimento de Evolución a Largo Plazo (LTEE), iniciado por Richard Lenski en 1988. Este estudio en curso ha seguido poblaciones de Escherichia coli cultivadas en un medio con glucosa limitada durante más de 80.000 generaciones. Con el tiempo, estos linajes han evolucionado diversas adaptaciones, incluyendo un aumento del tamaño celular, tasas de crecimiento más rápidas y vías metabólicas optimizadas.<h3>Evolución de la utilización del citrato</h3>Lo más notable es que una línea evolucionó la capacidad de metabolizar el citrato en condiciones aeróbicas, un rasgo típicamente ausente en E. coli silvestre, que no puede importar citrato en presencia de oxígeno. Esta innovación permitió a la cepa mutante explotar un recurso que de otro modo sería inaccesible, obteniendo una ventaja selectiva significativa.Los análisis genéticos revelaron que este rasgo surgió a través de una serie de mutaciones: inicialmente estableciendo el potencial de utilización de citrato (potenciación), seguidas de mutaciones que permitían su expresión y transporte real (actualización). Este hallazgo pone de manifiesto la interacción entre contingencia, mutación y selección natural en la innovación evolutiva.En conjunto, estos estudios ejemplifican cómo los sistemas microbianos actúan como modelos dinámicos para observar procesos evolutivos en tiempo real. Muestran tanto fuerzas deterministas como eventos estocásticos que impulsan la diversidad biológica y la innovación.

Evolución de nuevos rasgos en microbios

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

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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 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

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How Microbes Gain New Traits

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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...

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Microbial Core and Pan-Genome Changes

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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

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