The Influence of Glycine Betaine on Dimethyl Sulfide and Dimethylsulfoniopropionate Concentrations in Seawater

Abstract

We investigated whether additions of a common methylated osmolyte, glycine betaine (GBT), affected the concentrations of dimethyl sulfide (DMS) and its principal precursor, 3-dimethylsulfoniopropionate (DMSP) in seawater samples. DMS concentrations were frequently elevated by additions of GBT over the concentration range 0.125-5 µM. Additions of other methylated amines including choline and trimethylamine also increased DMS concentrations but to a lesser degree than did GBT. Nonmethylated compounds such as glucose, glycine, or acrylate had no effect on DMS concentrations. GBT affected both particulate and dissolved pools of DMSP. The addition of 5µ.M GBT to a natural assemblage of growing phytoplankton decreased the production of particulate DMSP but not that of chlorophyll a. GBT substantially inhibited the consumption of dissolved DMSP (DMSPdiss) and the production of DMS from DMSPdiss. Inhibition of DMSPdiss consumption resulted in a buildup of this pool which was only transient in some cases. As the consumption of DMSPdiss resumed, DMS production was stimulated. Our findings suggest DMS and DMSP concentrations may be influenced by naturally occurring compounds such as GBT.