Distribution and Dimethylsulfoniopropionate Degradation of Dimethylsulfoniopropionate‐Consuming Bacteria in the Yellow Sea and East China Sea

The fate of dimethylsulfoniopropionate (DMSP), the precursor of the climatologically important gas dimethylsulfide (DMS), depends on the structure of marine communities. DMSP degradation by DMSP‐consuming bacteria (DCB) is an important sink of dissolved DMSP (DMSPd) in seawater. DMSP cleavage and demethylation are two DMSPd consumption pathways, and the DMSPd cleavage pathway involves DMSP lyase activity (DLA). Here, we studied the distribution of DMS, DMSP, DCB, and DLA in the seawater of the Yellow Sea and East China Sea in the summer of 2013 and the degradation of DMSPd by DCB. High DCB abundances, as well as DMS and dissolved, particulate, total DMSP (DMSPd,p,t) concentrations were observed near the Hongzhou Bay, which may be due to the high productivity of dinoflagellates. The spatial distribution of DCB abundance was most likely the result of the regional hydrography including upwelling near Hangzhou Bay and the discharge of Yangtze Diluted Water (YDW). The DLA along the YDW decreased from coastal water to open sea. The DMSPd consumption by DCB Bacillus sp. YES023 isolated from the seawater was accompanied by DMS production (≤8.2% of DMSPd consumption). Bacillus sp. YES023 could also grow using glycine betaine, acrylic acid, dimethylsulfoxide, monomethylamine, or dimethylamine as a sole carbon source. Glycine betaine and acrylic acid were the most favorable substrates for overall growth. These results help our understanding of bacterial catabolism and the degradation pathways of methyl sulfur compounds in the ocean. Plain Language Summary Bacterial catabolism of dissolved dimethylsulfoniopropionate (DMSP) (DMSPd) is an important sink of DMSP in seawater. There are two DMSPd consumption pathways (DMSP cleavage and demethylation), and the dimethylsulfide (DMS)‐producing (DMSP cleavage) pathway involves DMSP lyase activity (DLA). In this study, we evaluated the DMS, DMSP, DMSP‐consuming bacteria (DCB) abundance, and DLA distributions in the seawater of the Yellow Sea and East China Sea. DCB in the seawater were isolated and identified. The degradation of DMSPd by and the bioavailability of the other five organic carbon analog of DMSP (including glycine betaine, acrylic acid, dimethylsulfoxide, monomethylamine, and dimethylamine) to DCB Bacillus sp. YES023 were investigated. Key Points Dimethylsulfoniopropionate (DMSP)‐consuming bacteria abundance and DMSP lyase activity were evaluated DMSP consumption by Bacillus sp. YES023 was accompanied by dimethylsu