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Fijación de nitrógeno por espiroquetas simbióticos y de vida libre
T G Lilburn1, K S Kim, N E Ostrom
1Ribosomal Database Project, Center for Microbial Ecology, Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824-1101, USA.
Science (New York, N.Y.)
|June 30, 2001
Resumen
Las espiroquetas, anteriormente desconocidas para fijar nitrógeno, poseen actividad nitrogenasa. Este descubrimiento los implica en la nutrición de las termitas y el ciclo global del nitrógeno, lo que podría explicar los genes nitrogenasa no asignados.
Área de la Ciencia:
- Microbiología Microbiología.
- La bioquímica es la bioquímica.
- Ciencias del medio ambiente Ciencias del medio ambiente.
Sus antecedentes:
- Las espiroquetas son un grupo diverso de bacterias, que se encuentran comúnmente en diversos entornos, incluidas las tripas y los sedimentos de los animales.
- La fijación del nitrógeno, la conversión del nitrógeno atmosférico en amoníaco, es un proceso crucial para la vida.
- El gen de la nitrogenasa (nifH) es un indicador clave de la capacidad de fijación de nitrógeno.
Objetivo del estudio:
- Para investigar la presencia de homólogos del gen de la nitrogenasa y la actividad de la nitrogenasa en las espiroquetas.
- Determinar el papel de las espiroquetas en la nutrición de nitrógeno, particularmente en las termitas.
- Explorar las implicaciones de la fijación de nitrógeno de las espiroquetas en el ciclo global del nitrógeno.
Principales métodos:
- Cribado de los genomas de espiroquetas de las entrañas de las termitas y los sedimentos de agua dulce para los homólogos del gen nifH.
- Evaluación de la actividad de la nitrogenasa en aislamientos de espiroquetas seleccionados, incluidos los intestinos de termitas Treponema ZAS-9 y Spirochaeta aurantia.
- Analizando la presencia de homólogos de nifH en treponemas orales y ruminales.
Principales resultados:
- Se encontró que los espiroquetas de las tripas y los sedimentos de las termitas poseían homólogos del gen nifH.
- Actividad nitrogenasa demostrada en estas espiroquetas, un hallazgo novedoso para este filo.
- Se han identificado homólogos de nifH en treponemas orales humanos y ruminantes bovinos.
- Se ha confirmado la fijación de 15-dinitrógeno en Treponema ZAS-9 y Spirochaeta aurantia.
Conclusiones:
- Las espiroquetas poseen la capacidad metabólica para la fijación de nitrógeno.
- Es probable que las espiroquetas contribuyan a la nutrición de nitrógeno de las termitas y al ciclo global del nitrógeno.
- Las espiroquetas pueden representar una fuente de genes nifH no asignados previamente en muestras ambientales.
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