11.11
Microbios y cambio climático
Los microorganismos son agentes clave en los ciclos biogeoquímicos de la Tierra, influyendo significativamente en la dinámica climática a través de su…
Los microbios desempeñan un papel central en los ciclos biogeoquímicos globales y pueden influir en la cantidad de gases de efecto invernadero liberados o absorbidos a medida que cambian las condiciones ambientales.
El aumento de las temperaturas globales acelera el metabolismo microbiano, incrementando la descomposición de la materia orgánica.
En condiciones ricas en oxígeno, esta descomposición libera dióxido de carbono a través de la respiración microbiana, contribuyendo a las emisiones de gases de efecto invernadero.
Pero, en ambientes con bajo oxígeno, como humedales o intestinos rumiantes, las arqueas metanogénicas pueden generar metano, un gas de efecto invernadero más potente que el dióxido de carbono.
Además, los microbios del suelo pueden producir óxido nitroso tanto durante la nitrificación como durante la desnitrificación, añadiendo otro gas de efecto invernadero a la atmósfera.
Algunos microbios ayudan a equilibrar estos efectos.
Por ejemplo, bacterias desnitrificantes como Paracoccus denitrificans convierten el óxido nitroso en gas nitrógeno inofensivo, reduciendo los niveles de gases de efecto invernadero.
Los microbios fotosintéticos marinos absorben dióxido de carbono para crecer, introduciéndolo en la cadena trófica. Parte de este carbono luego se hunde como células, desechos y material muerto en aguas más profundas.
View the full transcript and gain access to JoVE Core videos
Q1: How do rising temperatures affect microbial decomposition and greenhouse gas emissions?
Rising global temperatures accelerate microbial metabolism, speeding up the decomposition of organic matter. In oxygen-rich conditions, this decomposition releases carbon dioxide through microbial respiration, contributing to atmospheric greenhouse gas levels. Additionally, thawing permafrost activates dormant microbial communities, whose growth and metabolism emit both CO₂ and methane.
Q2: Why is methane produced in low-oxygen environments more concerning than carbon dioxide?
Methanogenic archaea in anaerobic environments like wetlands and ruminant guts generate methane, which is 25 to 30 times more potent than carbon dioxide at trapping atmospheric heat over a 100-year period. This greater warming potential makes methane a particularly significant contributor to climate change despite lower atmospheric concentrations.
Q3: What role do soil bacteria play in nitrous oxide emissions?
Soil bacteria such as Nitrosomonas and Pseudomonas produce nitrous oxide during nitrification and denitrification in the nitrogen cycle. Nitrous oxide is nearly 300 times more potent than carbon dioxide at trapping heat and also contributes to ozone layer depletion, making it a particularly harmful greenhouse gas.
Q4: How do denitrifying bacteria help mitigate climate change?
Denitrifying bacteria like Paracoccus denitrificans convert nitrous oxide into nitrogen gas during the final step of denitrification, a harmless atmospheric component. This process reduces the concentration of a potent greenhouse gas, helping to lower overall atmospheric warming potential and supporting climate change mitigation efforts.
Q5: What is the biological carbon pump and how do marine microbes contribute to it?
The biological carbon pump is the process by which marine photosynthetic microbes like Prochlorococcus absorb atmospheric carbon dioxide during photosynthesis. This carbon enters the food web and eventually sinks as cells, waste, and dead material into deeper ocean water, sequestering carbon long-term and helping regulate global climate.
Q6: How can methanotrophic bacteria reduce methane's climate impact?
Methanotrophic bacteria oxidize methane into carbon dioxide, converting a more potent greenhouse gas into a less harmful form. This microbial process reduces methane's atmospheric concentration and its contribution to climate warming, representing a natural mechanism for mitigating one of the most significant greenhouse gases.
Q7: What environmental factors influence microbial greenhouse gas production and mitigation?
Oxygen levels, moisture, and nutrient availability greatly influence whether microbes produce or mitigate greenhouse gases. Understanding these environmental factors and their effects on microbial pathways presents opportunities for developing innovative climate change mitigation strategies through microbial bioremediation and other harnessed microbial processes to reduce atmospheric greenhouse gas concentrations.