Grace Sim1, Cintia Iha1, Terry Pinfold2, Christopher Bolch1
1 Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
2 Tasmanian School of Medicine, University of Tasmania, Hobart, TAS, Australia
The phytoplankton and its’ constitutive microbiome have complex and dynamic inter-relationships, that may play a key role in driving the Earth’s global biogeochemical systems. Microbiomes colonise both the surface and micro-region around phytoplankton cells (the phycosphere). Both laboratory and field studies show that specific, active microbiomes are essential for phytoplankton growth, and are distinct from the much more abundant “background” microbial community. Despite their apparent importance, we currently know very little about the diversity, structure, and function of natural microbiomes. Using phytoplankton fluorescence characteristics, we aimed to identify and sort individual phytoplankton species and their surface-associated microbiomes directly from natural samples using a MoFlo Astrios EQ flow cytometer. To date we have successfully sorted the dinoflagellates Tripos furca and Gymnodinium catenatum from multiple natural phytoplankton blooms. Using this method, we have reliably sorted up to 500 cells of the same species multiple times with the same or different samples. Here we compare microbiome diversity obtained by direct microbial profiling (16S rRNA, Illumina) with the culturable microbiome recovered from flow-sorted dinoflagellate cells using traditional isolation and sequencing approaches. Both methodologies demonstrated differences in the community composition between the background environmental flora and the targeted phycosphere microbiome.