Emission spectroscopy and kinetic fluorometry studies of phototrophic microbial communities along a salinity gradient in solar saltern evaporation ponds of Eilat, Izrael
Abstract
The microbial communities in 8 hypersaline evaporation ponds in Eilat, Israel, with salinities from 58 to 329 g l–1, were studied using fluorescence emission spectroscopy and kinetic fluorometry. With increasing salinity, the anoxygenic phototrophic bacteria formed a significant and increasing fraction of the planktonic phototrophic biomass.
While the bchl a/chl a molar ratio was 0.01 at the lowest salinity, it reached almost 1 at the higher salinities. In the benthos, emission spectroscopy revealed depth-dependent changes in the physiology of oxygenic phototrophs, and spatial variability in the abundance of of anoxygenic photosynthetic bacteria.
The emission signal of the benthic phototrophs was dominated by photosystem I (detected in some cases down to 5 cm of sediment depth). The signal of photosystem II and phycobilisomes was several times weaker and was observed mostly in the surface layers.
The spectroscopic data of communities were complemented by microscopic characterizatio