Anoxygenic photosynthesis controls oxygenic photosynthesis in a cyanobacterium from a sulfidic spring.

Autor:	Klatt JM; Max Planck Institute for Marine Microbiology, Bremen, Germany jklatt@mpi-bremen.de., Al-Najjar MA; Max Planck Institute for Marine Microbiology, Bremen, Germany Red Sea Research Center, KAUST, Thuwal, Saudi Arabia., Yilmaz P; Max Planck Institute for Marine Microbiology, Bremen, Germany., Lavik G; Max Planck Institute for Marine Microbiology, Bremen, Germany., de Beer D; Max Planck Institute for Marine Microbiology, Bremen, Germany., Polerecky L; Max Planck Institute for Marine Microbiology, Bremen, Germany Department of Earth Sciences-Geochemistry, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands.
Jazyk:	angličtina
Zdroj:	Applied and environmental microbiology [Appl Environ Microbiol] 2015 Mar; Vol. 81 (6), pp. 2025-31. Date of Electronic Publication: 2015 Jan 09.
DOI:	10.1128/AEM.03579-14
Abstrakt:	Before the Earth's complete oxygenation (0.58 to 0.55 billion years [Ga] ago), the photic zone of the Proterozoic oceans was probably redox stratified, with a slightly aerobic, nutrient-limited upper layer above a light-limited layer that tended toward euxinia. In such oceans, cyanobacteria capable of both oxygenic and sulfide-driven anoxygenic photosynthesis played a fundamental role in the global carbon, oxygen, and sulfur cycle. We have isolated a cyanobacterium, Pseudanabaena strain FS39, in which this versatility is still conserved, and we show that the transition between the two photosynthetic modes follows a surprisingly simple kinetic regulation controlled by this organism's affinity for H2S. Specifically, oxygenic photosynthesis is performed in addition to anoxygenic photosynthesis only when H2S becomes limiting and its concentration decreases below a threshold that increases predictably with the available ambient light. The carbon-based growth rates during oxygenic and anoxygenic photosynthesis were similar. However, Pseudanabaena FS39 additionally assimilated NO3 (-) during anoxygenic photosynthesis. Thus, the transition between anoxygenic and oxygenic photosynthesis was accompanied by a shift of the C/N ratio of the total bulk biomass. These mechanisms offer new insights into the way in which, despite nutrient limitation in the oxic photic zone in the mid-Proterozoic oceans, versatile cyanobacteria might have promoted oxygenic photosynthesis and total primary productivity, a key step that enabled the complete oxygenation of our planet and the subsequent diversification of life. (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
Databáze:	MEDLINE
Externí odkaz:	Zobrazit plný text záznamu