T267 Critical Zone Science—Bio-Geo Interactions across Environmental Gradients and Time (Posters)

Wednesday, 7 November 2018
9:00 AM - 6:30 PM
Halls J-K

THE IMPACT OF TERRIGENOUS IRON GRADIENTS ON CHROMATIC ACCLIMATION OF MARINE CYANOBACTERIA

Paper number: T267-1
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

Synechococcus spp., a picocyanobacteria, is one of the most abundant and ubiquitous phytoplankton in the world’s oceans. They are found in a variety of oceanic environments including turbid, optically clear, nutrient rich, and oligotrophic waters. Some strains undergo chromatic acclimation (CA), a process whereby photosynthetic pigments are optimized to harvest ambient wavelengths of light. This optimization is observed as a change in the relative expression of chromophores of the accessory pigment phycoerythrin: cyan-absorbing phycourobilin (PUB); and green-absorbing phycoerythrobilin (PEB). The PUB:PEB range is 1.2-1.4 in blue LED light and decreases to 0.3-0.5 in green or white LED light. Our lab experiments reveal that available dissolved iron (Fe’) concentrations, independent of light color, trigger small changes in protein expression and PUB:PEB within some Synechococcus chromatic adapters. Iron replete conditions (>1nM Fe’) produce lower PUB:PEB while iron starved conditions (<0.1nM Fe’) increases PUB:PEB. This has been observed in the chromatic adapter strains WH 8020 and RCC 2673. Optimization for blue light-harvesting (higher PUB:PEB) at low iron concentrations could indicate that trace elements, as well as light color, are triggers for light acclimation responses for cyanobacteria in the ocean.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-317867

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