Rhizobium free-living nitrogen fixation occurs in specialized nongrowing cells
AUTOR(ES)
Ludwig, Robert A.
RESUMO
A model for free-living N2 fixation by Rhizobium sp. RC3200 is presented that asserts that this process occurs in nongrowing cells. Cultures containing mixed populations of cell types, N2-fixing and vegetative, grow cooperatively. In nitrogen-limited liquid suspension cultures, cooperative growth occurs by means of ammonium that is produced and exported by nongrowing, N2-fixing cells and transported to vegetative cells. This model implies prokaryotic differentiation: the creation of metabolically specialized cells, terminally nonviable, that functionally cooperate in a higher cell order. Here, the switch to a Rhizobium N2-fixing cell state is regulated by both O2 and utilizable nitrogen.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=344878Documentos Relacionados
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