Photoacclimation by Arctic cryoconite phototrophs
Cryoconite is a matrix of sediment, biogenic polymer and a microbial community which resides on glacier surfaces. The phototrophic component of this community is well adapted to this extreme environment, including high light stress. Photoacclimation of the cryoconite phototrophic community on Longye...
| Published in: | FEMS Microbiology Ecology |
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| Main Authors: | , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Oxford University Press
2017
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| Subjects: | |
| Online Access: | http://eprints.uwe.ac.uk/30998/ http://eprints.uwe.ac.uk/30998/1/Perkins%20et%20al%20Cryoconite%20Photoacclimation%20FEMS%202017.pdf https://doi.org/10.1093/femsec/fix018 |
| Summary: | Cryoconite is a matrix of sediment, biogenic polymer and a microbial community which resides on glacier surfaces. The phototrophic component of this community is well adapted to this extreme environment, including high light stress. Photoacclimation of the cryoconite phototrophic community on Longyearbreen, Svalbard was investigated using in situ variable chlorophyll fluorescence. Rapid light curves (RLCs) and induction recovery curves were used to analyse PSII quantum efficiency, relative electron transport rate and forms of down regulation including non-photochemical quenching (NPQ) and state transitions in cyanobacteria. Phototrophs used a combination of behavioural and physiological photochemical down regulation. Behavioural down regulation is hypothesised to incorporate chloroplast movement and cell or filament positioning within the sediment matrix in order to shade from high light, which resulted in a lack of saturation of RLCs and hence overestimation of productivity. Physiological down regulation likely consisted of biphasic NPQ: comprising a steadily induced light-dependent form and a light-independent NPQ that was not reversed with decreasing light intensity. State transitions by cyanobacteria was the most likely physiological down regulation employed by cyanobacteria within the mixed phototroph community. These findings demonstrate that cryoconite phototrophs combine multiple forms of physiological and behavioural down regulation to optimise light exposure and maximise photosynthetic productivity. This plasticity of photoacclimation enables them to survive productively in the high light stress environment on the ice surface. |
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