Production of dimethyl sulfide and acrylic acid from dissolved dimethylsulfoniopropionate during the growth of Prorocentrum minimum

Dimethyl sulfide (DMS) is an important and dominant trace gas that is transferred from the ocean to the atmosphere; however, the production of DMS from marine algae is still rudimentary, with the enzymatic cleavage of dimethylsulfoniopropionate (DMSP) to DMS and acrylic acid (AA), one of the main considered pathways. Dissolved DMSP (DMSPd) was supplied to batch cultures of Prorocentrum minimum at different algal growth stages and the kinetics of overall DMSPd consumption and DMS (AA) production were investigated. The kinetics of overall DMSPd consumption and DMS (AA) production from DMSPd were different during the growth cycle. The cultures displayed Michaelis-Menten-type kinetics for DMS production during the entire growth period, which yielded an apparent half-saturation constant (K-m(app)) value of 37.8 +/- 12.8 mu M and a maximum rate (V-max) value of 75.6 +/- 12.2 nmol min(-1) (10(10) cells)(-1). The production rates of AA had a nearly linear fit over the concentration range of the added DMSPd except during mid-exponential growth phase. A K-m(app) value of 1.73 +/- 0.75 mu M and a V-max value of 2.36 +/- 0.12 mu mol min(-1) (10(10) cells)(-1) were observed. The ratio of DMS/AA increased with the concentration of the added DMSPd, which was less than 12% during the entire growth period. The low ratios of DMS/(DMSP + AA), which ranged from 0.01 to 1.83%, demonstrate that degradation of DMSP tends to take a non-DMS-production pathway. The ratios of AA/(DMSP + AA) varied from 9 to 95% during the stationary phase and from 6 to 69% during the senescent phase and declined with substrate concentration when different concentrations of DMSPd were added. The degradation ratios of DMSPd were related to the initial concentrations of DMSPd.