No abstract

Using nuclear magnetic resonance spectroscopy, we identified and characterized accumulated compatible solutes in cells of the haptophyte alga Pavlova sp. strain CCMP504. The predominant organic solutes were D-1,4/2,5-cyclohexanetetrol (CHT), 1,3,5/2,4-cyclohexanepentol (CHP) and scyllo-inositol. We then profiled the intracellular organic solutes present in Pavlova sp. grown in medium with salinity ranging from 23 practical salinity units (PSU) (hyposaline) to 35 PSU (optimum salinity for growth), to 47 PSU (hypersaline). The results of these analyses reveal progressive accumulation of CHT and CHP in response to increasing growth medium salinity. We also observed altered accumulation of CHT and CHP in samples subjected to salinity shock. To further characterize the CHT and CHP biosynthesis in Pavlova sp., we carried out stable isotope feeding experiments. Specific labeling of CHT and CHP with D-13 C-glucose suggested that D-glucose is a biosynthetic precursor of these cyclitols. The salinity-induced accumulation of CHT and CHP suggests that these cyclitols act as compatible solutes. Our results therefore provide new evidence supporting classification of CHP as a compatible solute.