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La racionalización metabólica en una cianobacterium fijador de nitrógeno de mar abierto
H James Tripp1, Shellie R Bench, Kendra A Turk
1Ocean Sciences Department, University of California, Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA.
Nature
|February 23, 2010
Resumen
Las cianobacterias marinas UCYN-A, que carecen de fotosíntesis oxigenada, utilizan un metabolismo fotofermentativo único. Este organismo fijador de nitrógeno depende de otros para obtener nutrientes esenciales, lo que pone de relieve la interdependencia microbiana en los océanos.
Área de la Ciencia:
- Microbiología marina microbiología marina.
- Biogeoquímica La biogeoquímica es la bioquímica.
- La genómica es la genómica.
Sus antecedentes:
- Las cianobacterias marinas fijadoras de nitrógeno (N2) son cruciales para la productividad primaria oceánica y la eliminación de dióxido de carbono atmosférico.
- El cianobacterium UCYN-A distribuido globalmente carece de fotosistema II, lo que sugiere un nuevo metabolismo, pero permanece sin cultivar.
Objetivo del estudio:
- Aclarar las capacidades metabólicas y las dependencias nutricionales de la cianobacterium UCYN-A no cultivada.
- Comprender las adaptaciones evolutivas y el papel ecológico de UCYN-A en los ecosistemas marinos.
Principales métodos:
- El ensamblaje del genoma completo de UCYN-A mediante pirosecuenciación masiva paralela.
- Reconstrucciones metabólicas basadas en datos genómicos.
- Análisis de la estructura reducida del genoma y el contenido genético de UCYN-A.
Principales resultados:
- UCYN-A posee un metabolismo fotofermentativo, generando energía y reduciendo la potencia de la luz.
- El organismo carece de las principales vías metabólicas como el ciclo del ácido tricarboxílico y las vías biosintéticas esenciales para los aminoácidos y las purinas.
- UCYN-A exhibe un genoma reducido (1.44 Mb) con similitudes estructurales con los cloroplastos y las bacterias, incluidos los operones de ARNr invertidos.
Conclusiones:
- UCYN-A es metabólicamente dependiente de otros organismos para los nutrientes esenciales, probablemente a través de una estrecha asociación o simbiosis.
- Los hallazgos revelan UCYN-A como una paradoja en la evolución y adaptación microbiana, lo que demuestra un estrecho acoplamiento metabólico en entornos oligotróficos.
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