Dimethylsulfide production from dimethylsulfonio-propionate by a marine bacterium

Abstract

The processes of dimethylsulfoniopropionate (DMSP) uptake and dirnethylsulfide (DMS) production from DMSP were investigated using a marine bacterium isolated from Sargasso Sea water. Uptake of DMSP into the cell preceded cleavage to form DMS, indicating an intracellular location for the DMSP lyase. The rate of DMS production accelerated rapidly during the timecourse of DMSP cleavage, independent of cell growth; this increase in rate was suppressed in the presence of 500 pM chloramphenicol, consistent with induction of the DMSP lyase. Additionally, preincubation with acrylic acid, the putative byproduct of the cleavage, as well as with DMSP, stimulated the initial rate of DMS production. Two determinations of the K,, V,,, values for DMSP uptake in induced cells yielded 190 nM, 1.3 fmol cell-' h-' and 105 nM, 3.2 fmol cell-' h-' A single determination of these parameters in uninduced cells yielded 280 nM and 1.9 fmol cell-' h-'. The rate of DMS production from DMSP exhibited a sigmoidal dependence on extracellular DMSP concentration.