Photoacclimation by Arctic cryoconite phototrophs

Rupert G Perkins, Elizabeth Bagshaw, Lisa Mol, Christopher J Williamson, Dan T Fagan, Maggie L Gamble, Marian L Yallop

Research output: Contribution to journalArticle (Academic Journal)

4 Citations (Scopus)
221 Downloads (Pure)

Abstract

Cryoconite is a matrix of sediment, biogenic polymer and a microbial community that 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 photosystem II quantum efficiency, relative electron transport rate and forms of downregulation including non-photochemical quenching (NPQ) and state transitions in cyanobacteria. Phototrophs used a combination of behavioural and physiological photochemical downregulation. Behavioural downregulation 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 downregulation 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 were the most likely physiological downregulation employed by cyanobacteria within the mixed phototroph community. These findings demonstrate that cryoconite phototrophs combine multiple forms of physiological and behavioural downregulation 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.
Original languageEnglish
Article numberfix018
Number of pages10
JournalFEMS Microbiology Ecology
Volume93
Issue number5
Early online date18 Feb 2017
DOIs
Publication statusPublished - May 2017

Keywords

  • cryoconite
  • photoacclimation
  • downregulation
  • non-photochemical quenching
  • productivity
  • fluorescence

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