Pyrosequencing of dddP genes revealed SAR116 clade as dominant DMSproducing bacteria in oligotrophic NW Pacific Ocean

초록

Dimethylsulfide (DMS) has been known to be a climatically active gas released into the atmosphere from oceans. The DMS is produced mainly by bacterial enzymatic cleavage of dimethylsulfoniopropionate (DMSP) and several DMSP lyases have been identified to date. To elucidate biogeographical distribution of bacteria relevant to DMS production, in this study, the diversity of dddP, which is most abundant DMS-producing gene, was investigated using newly developed primers and pyrosequencing method in the northwestern Pacific Ocean. Consistently with the previous studies, Roseobacters were major dddP-containing bacteria in coastal area. However, the genotypes closely related with SAR116 group were found to be a predominant fraction of dddP-containing bacteria in surface water of oligotrophic ocean. A DMSP-enriched culture experiment of SAR116 strain, Puniceispirillum marinum IMCC1322, showed that the strain can produce DMS from DMSP. Considering the huge area of oligotrophic waters and wide distribution of SAR116 group in the global ocean, they may play a significant role in climatically important DMS production and should be surely encompassed in biogeochemical studies of sulfur via bacteria-mediated DMSP degradation.