UNRAVELING THE INFECTION DYNAMICS AND BIOGEOCHEMICAL EFFECTS OF PARASITIC MARINE PROTISTS USING A MULTI-OMICS APPROACH

Parasitic protists in the alveolate group, Syndiniales, are highly diverse and prevalent in global marine and freshwater habitats. However, Syndiniales parasite-host infection dynamics remain unclear, including strain-level variability and the influence of parasitism on carbon cycling and bacterial consumption of labile dissolved organic matter (DOM). Here, we used multiple ‘omics methods to explore infection of the same dinoflagellate host, Scrippsiella acuminata, by two Syndiniales strains (4401 and 4390). Untargeted metabolomics revealed significant differences in the composition of extracellular metabolites between parasite strains, time over the infection cycle, and infected vs. host (and spore-only) controls. Specific features were significantly elevated (log2 fold) in infected treatments, representing compounds of interest that may indicate infection. Strain-level physiological differences were also observed, namely higher infection success (38% infected) for 4401 compared to 4390 (12%). Lastly, we performed an inoculation experiment with 4401 filtrate to examine bacterial responses via metabarcoding and metatranscriptomics. Initial results confirmed the rapid response of natural bacterial communities to labile DOM (6 hours) and revealed a shift in composition after 24-48 hours that favored copiotrophic taxa (e.g., Cytophagales). This work provides new insights into the strain-level infection dynamics and biogeochemistry of marine parasitic protists and reinforces the importance of integrating multiple ‘omics tools to better define parasitism in microbial food webs.

Presentation Preference: Oral

Primary Presenter: Sean Anderson, University of New Hampshire (seanceltics34@gmail.com)

Authors:

Sean Anderson, University of New Hampshire  (seanceltics34@gmail.com)

Philip Place, University of New Hampshire  (philip.place@unh.edu)

Kelsey Poulson-Ellestad, Roosevelt University  (kpoulsonellestad@roosevelt.edu)

Elizabeth Harvey, University of New Hampshire  (elizabeth.harvey@unh.edu)