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Dependence of the cyanobacterium Prochlorococcus on hydrogen peroxide scavenging microbes for growth at the ocean's surface.
- Source :
-
PloS one [PLoS One] 2011 Feb 03; Vol. 6 (2), pp. e16805. Date of Electronic Publication: 2011 Feb 03. - Publication Year :
- 2011
-
Abstract
- The phytoplankton community in the oligotrophic open ocean is numerically dominated by the cyanobacterium Prochlorococcus, accounting for approximately half of all photosynthesis. In the illuminated euphotic zone where Prochlorococcus grows, reactive oxygen species are continuously generated via photochemical reactions with dissolved organic matter. However, Prochlorococcus genomes lack catalase and additional protective mechanisms common in other aerobes, and this genus is highly susceptible to oxidative damage from hydrogen peroxide (HOOH). In this study we showed that the extant microbial community plays a vital, previously unrecognized role in cross-protecting Prochlorococcus from oxidative damage in the surface mixed layer of the oligotrophic ocean. Microbes are the primary HOOH sink in marine systems, and in the absence of the microbial community, surface waters in the Atlantic and Pacific Ocean accumulated HOOH to concentrations that were lethal for Prochlorococcus cultures. In laboratory experiments with the marine heterotroph Alteromonas sp., serving as a proxy for the natural community of HOOH-degrading microbes, bacterial depletion of HOOH from the extracellular milieu prevented oxidative damage to the cell envelope and photosystems of co-cultured Prochlorococcus, and facilitated the growth of Prochlorococcus at ecologically-relevant cell concentrations. Curiously, the more recently evolved lineages of Prochlorococcus that exploit the surface mixed layer niche were also the most sensitive to HOOH. The genomic streamlining of these evolved lineages during adaptation to the high-light exposed upper euphotic zone thus appears to be coincident with an acquired dependency on the extant HOOH-consuming community. These results underscore the importance of (indirect) biotic interactions in establishing niche boundaries, and highlight the impacts that community-level responses to stress may have in the ecological and evolutionary outcomes for co-existing species.
- Subjects :
- Adaptation, Physiological physiology
Aquatic Organisms physiology
Biota
Cyanobacteria growth & development
Cyanobacteria metabolism
Cyanobacteria physiology
Ecosystem
Oceans and Seas
Oxidative Stress physiology
Pacific Ocean
Photosynthesis physiology
Phylogeny
Prochlorococcus metabolism
Prochlorococcus physiology
Symbiosis physiology
Aquatic Organisms metabolism
Free Radical Scavengers metabolism
Hydrogen Peroxide metabolism
Prochlorococcus growth & development
Subjects
Details
- Language :
- English
- ISSN :
- 1932-6203
- Volume :
- 6
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- PloS one
- Publication Type :
- Academic Journal
- Accession number :
- 21304826
- Full Text :
- https://doi.org/10.1371/journal.pone.0016805