Universität zu Köln

Bothe, Hermann, Tripp, H. James and Zehr, Jonathan P. (2010). Unicellular cyanobacteria with a new mode of life: the lack of photosynthetic oxygen evolution allows nitrogen fixation to proceed. Arch. Microbiol., 192 (10). S. 783 - 791. NEW YORK: SPRINGER. ISSN 1432-072X

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Abstract

Some unicellular N-2-fixing cyanobacteria have recently been found to lack a functional photosystem II of photosynthesis. Such organisms, provisionally termed UCYN-A, of the oceanic picoplanktion are major contributors to the global marine N-input by N-2-fixation. Since their photosystem II is inactive, they can perform N-2-fixation during the day. UCYN-A organisms cannot be cultivated as yet. Their genomic analysis indicates that they lack genes coding for enzymes of the Calvin cycle, the tricarboxylic acid cycle and for the biosynthesis of several amino acids. The carbon source in the ocean that allows them to thrive in such high abundance has not been identified. Their genomic analysis implies that they metabolize organic carbon by a new mode of life. These unicellular N-2-fixing cyanobacteria of the oceanic picoplankton are evolutionarily related to spheroid bodies present in diatoms of the family Epithemiaceae, such as Rhopalodia gibba. More recently, spheroid bodies were ultimately proven to be related to cyanobacteria and to express nitrogenase. They have been reported to be completely inactive in all photosynthetic reactions despite the presence of thylakoids. Sequence data show that R. gibba and its spheroid bodies are an evolutionarily young symbiosis that might serve as a model system to unravel early events in the evolution of chloroplasts. The cell metabolism of UCYN-A and the spheroid bodies may be related to that of the acetate photoassimilating green alga Chlamydobotrys.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Bothe, Hermann UNSPECIFIED UNSPECIFIED UNSPECIFIED Tripp, H. James UNSPECIFIED UNSPECIFIED UNSPECIFIED Zehr, Jonathan P. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-494645
DOI:	10.1007/s00203-010-0621-5
Journal or Publication Title:	Arch. Microbiol.
Volume:	192
Number:	10
Page Range:	S. 783 - 791
Date:	2010
Publisher:	SPRINGER
Place of Publication:	NEW YORK
ISSN:	1432-072X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language VON CHLAMYDOBOTRYS VOLVOCALES; SUBTROPICAL NORTH PACIFIC; N-2 FIXATION; DIAZOTROPHIC CYANOBACTERIA; CYANOPHORA-PARADOXA; SPHEROID BODIES; PHOTOSYSTEM-II; OCEAN; RHOPALODIA; PHYLOGENY Multiple languages Microbiology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/49464