Different dimethylsulphoniopropionate-producing ability of dinoflagellates could affect the structure of their associated bacterial community

Abstract Dinoflagellate plays an important role in the production of dimethylsulphoniopropionate (DMSP) in marine ecosystem. DMSP derived from dinoflagellates is an important reducing sulfur and carbon source for heterotrophic bacterioplankton. Although dinoflagellates have outstanding ability in DMSP biosynthesis, and the inter-specific variation of cellular DMSP concentrations in different species and strains has been well described, the effects of DMSP level on microbial community structure are still unclear. In this study, the ability of seven dinoflagellates to synthesize DMSP and their effects on the composition of associated bacterial community were investigated. Total concentration of DMSP (2397.25 ± 187.17 μM) and single cell DMSP content (34.25 ± 2.67 pmol cell−1) were the highest in Protoceratium reticulatum, while the DMSP contents of Prorocentrum texanum and Amphidinium carterae were significantly lower than those of other dinoflagellates. Bacterial community structure in dinoflagellate culture was determined by cultivation-dependent and cultivation-independent approaches. There were significantly differences in the richness and diversity of bacteria in different dinoflagellate cultures with different DMSP contents. In addition, abundant of Roseobacter-clade bacteria (well-known DMSP degraders) were found in the cultures of six dinoflagellates. Genomic analysis indicated that the Roseobacter-clade bacteria isolated from dinoflagellate could degrade DMSP by cleavage pathway. The results demonstrated that DMSP could be an important factor affecting the abundance and composition of bacterial community in phycosphere of dinoflagellates.