Nitrogen-fixing cyanobacteria are tuned for evolvability

Cyanobacteria produce a significant fraction of the oxygen on the environment and, together with archaea, they fix atmospheric nitrogen used by all other organisms. One of the first forms of multicellular organisms on Earth are filamentous cyanobacteria, which constitutCyanobacteria produce a significant fraction of the oxygen on the environment and, together with archaea, they fix atmospheric nitrogen used by all other organisms. One of the first forms of multicellular organisms on Earth are filamentous cyanobacteria, which constitute a paradigmatic model organism of the transition between unicellular and multicellular living forms. The genus Anabaena forms colonies with cells arranged in one-dimensional filaments; under nitrogen-limiting conditions some cells can differentiate into a nitrogen-fixing heterocysts, forming regular patterns to effectively provide nitrogen for the colony. e a paradigmatic model organism of the transition between unicellular and multicellular living forms. The genus Anabaena forms colonies with cells arranged in one-dimensional filaments; under nitrogen-limiting conditions some cells can differentiate into a nitrogen-fixing heterocysts, forming regular patterns to effectively provide nitrogen for the colony..