title: Cyanophycin mediates the accumulation and storage of fixed carbon in non-heterocystous filamentous cyanobacteria from coniform mats.
abstract: Thin, filamentous, non-heterocystous, benthic cyanobacteria (Subsection III) from some marine, lacustrine and thermal environments aggregate into macroscopic cones and conical stromatolites. We investigate the uptake and storage of inorganic carbon by cone-forming cyanobacteria from Yellowstone National Park using high-resolution stable isotope mapping of labeled carbon (H(13)CO3 (-)) and immunoassays. Observations and incubation experiments in actively photosynthesizing enrichment cultures and field samples reveal the presence of abundant cyanophycin granules in the active growth layer of cones. These ultrastructurally heterogeneous granules rapidly accumulate newly fixed carbon and store 18% of the total particulate labeled carbon after 120 mins of incubation. The intracellular distribution of labeled carbon during the incubation experiment demonstrates an unexpectedly large contribution of PEP carboxylase to carbon fixation, and a large flow of carbon and nitrogen toward cyanophycin in thin filamentous, non-heterocystous cyanobacteria. This pattern does not occur in obvious response to a changing N or C status. Instead, it may suggest an unusual interplay between the regulation of carbon concentration mechanisms and accumulation of photorespiratory products that facilitates uptake of inorganic C and reduces photorespiration in the dense, surface-attached communities of cyanobacteria from Subsection III.
authors: Institute of Earth Sciences, Academia Sinica, Nangang, Taipei, Taiwan, ROC ; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America ; Department of Earth Sciences, National Cheng Kung University, Tainan 701, Taiwan, ROC.
authors: Biqing
authors: B
authors: Liang
authors: INSERM, U759, Orsay, France ; Institut Curie, Laboratoire de Microscopie Ionique, Orsay, France.
authors: Ting-Di
authors: TD
authors: Wu
authors: Department of Life Sciences, National Central University, Jhongli City, Taiwan, ROC.
authors: Hao-Jhe
authors: HJ
authors: Sun
authors: Facility for Electron Microscopy Research, McGill University, Montreal, Canada ; Department of Anatomy and Cell Biology, McGill University, Montreal, Canada.
authors: Hojatollah
authors: H
authors: Vali
authors: INSERM, U759, Orsay, France ; Institut Curie, Laboratoire de Microscopie Ionique, Orsay, France.
authors: Jean-Luc
authors: JL
authors: Guerquin-Kern
authors: Institute of Earth Sciences, Academia Sinica, Nangang, Taipei, Taiwan, ROC.
authors: Chung-Ho
authors: CH
authors: Wang
authors: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors: Tanja
authors: T
authors: Bosak
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle / Q000502:physiology*; D000458:Cyanobacteria / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C024250:cyanophycin; D002244:Carbon; D009584:Nitrogen