Dimethyl sulfide (DMS) and dimethylsulfoniopropionate (DMSP) are sulfur compounds that may function as antioxidants in algae. Symbiotic dinoflagellates of the genus Symbiodinium show strain-specific differences in their susceptibility to temperature-induced oxidative stress and have been shown to contain high concentrations of DMSP. We investigated continuous cultures of four strains from distinct phylotypes (A1, A13, A2, and B1) that can be characterized by differential thermal tolerances. We hypothesized that strains with high thermal tolerance have higher concentrations of DMSP and DMS in comparison to strains with low thermal tolerance. DMSP concentrations were strain-specific with highest concentrations occurring in A1 (225 ± 3.5 mmol · L(-1 ) cell volume [CV]) and lowest in A2 (158 ± 3.8 mmol · L(-1 ) CV). Both strains have high thermal tolerance. Strains with low thermal tolerance (A13 and B1) showed DMSP concentrations in between these extremes (194 ± 19.0 and 160 ± 6.1 mmol · L(-1 ) CV, respectively). DMS data further confirmed this general pattern with high DMS concentrations in A1 and A13 (4.1 ± 1.22 and 2.1 ± 0.37 mmol · L(-1 ) CV, respectively) and low DMS concentrations in A2 and B1 (0.3 ± 0.06 and 0.5 ± 0.22 mmol · L(-1) CV, respectively). Hence, the strain-specific differences in DMSP and DMS concentrations did not match the different abilities of the four phylotypes to withstand thermal stress. Future work should quantify the possible dynamics in DMSP and DMS concentrations during periods of high oxidative stress in Symbiodinium sp. and address the role of these antioxidants in zooxanthellate cnidarians.
Keywords: Symbiodinium; continuous culture; dimethyl sulfide (DMS); dimethylsulfoniopropionate (DMSP); strain specificity.
© 2011 Phycological Society of America.