Phaeocystis microbiome
Task 2.5: Water column phenomics: from cellular to environmental morphophysiological plasticity of the microalga Phaeocystis and its associated microbiomes [M1 – M48] Lead: CNRS-LPCV. The diversity and morpho-genetic flexibility of the potentially harmful planktonic microalga genus Phaeocystis and associated microbiome will be assessed across different life stages (solitary, colonial, symbiotic) and environmental EU gradients (T1.1). In T2.5.1 CNRS-LPCV will investigate at EU sampling sites (T1.1) the genetic diversity of Phaeocystis and its expressed genes together with potential microbial interactions assessed by co-occurrence analyses using both new prokaryotic sequences generated in T1.1 and time-series data (T1.3), with focus on Phaeocystis blooms, during which single colonies will be isolated for holobiont metaG and 3D electron microscopy. In T2.5.2 the volume (3D electron microscopy) and photo-physiological state of energy-producing organelles (chloroplast) of the different Phaeocystis species/life stages in different environmental conditions will be determined by CNRS-LPCV to infer correlations between morphometrics, transcriptomics and physiology. This imaging approach will also allow visualization of putative physical interactions with symbiotic bacteria. In T2.5.3 a microbiome will be re-established in vitro by mixing natural seawater with axenic Phaeocystis cultures. MetaG will unveil the temporal dynamics of microbiome establishment and bacteria will be isolated into clonal culture. The microbiome found associated with cultured Phaeocystis will be compared with the potential microbiome inferred in situ in T2.5.1.