[MIS25-P12] Interaction between marine bacterial community and dissolved organic matter released by pelagic phytoplankton
Keywords:Marine bacteria, Marine phytoplankton, Dissolved organic matter
FDOM analysis for initial samples (Day 0) showed that the fluorescence intensity of humic-like M, C, A from DOMPSynech amendments were higher than those of DOMPPelago. During incubation experiments, fluorescence intensity of protein-like B and T in the DOMPPelago decreased with time. After incubation (Day 5), decreases in humic-like M intensity were observed both in the DOMPSynech and DOMPPelago treatments. The 16S rRNA gene tag-sequence revealed the relative abundance of Oceanospirillales and Alteromonadales (affiliated with Gammaproteobacteria) to total 16S rRNA sequences drastically increased in both DOMP treatments on Day 1. However, an increase in Rhodobacterales (affiliated with Alphaproteobacteria) was observed on Day 5. Interestingly, the proliferation of Betaproteobacteria and Deltaproteobacteria (numerically rare lineages in surface seawater) occurred in the DOMPSynech and DOMPPelago treatments on Day 5, respectively.
These results suggest that the DOMPs released by distinct pelagic phytoplankton can affect the bacterial community structures including numerically rare lineages, and these lineages potentially contribute to the degradation of phytoplankton-derived humic-like materials in seawater.