Amino Acid Cycling in Colonies of the Planktonic Marine Cyanobacterium Trichodesmium thiebautii

摘要: We examined diel trends in internal pools and net efflux of free amino acids colonies the nonheterocystous, diazotrophic cyanobacterium Trichodesmium thiebautii, freshly collected from waters Caribbean Bahamas. The kinetics glutamate uptake by whole were also examined. While intracolonial most relatively constant through day, glutamine varied over cycle, with maxima during early afternoon. This paralleled daily cycle nitrogenase activity. observed a large release these two intact colonies. Glutamate was typically 100 pmol N colony h. is about one-fourth concurrent rate N(2) fixation day. However, while activity only occurs persisted into night may therefore account for greater loss recently fixed on basis. be an important route new input tropical, oligotrophic waters. Whole displayed saturation respect to uptake. K(s) 1.6 3.2 muM, or 100-fold than typical ambient concentrations. Thus, systems appear adapted higher concentrations found within intracellular spaces suggests that vehicle exchange among trichomes colony.