Guest Seminar: Zooming In on the Phycosphere

Speaker

Dr. Shady Amin
Assistant Professor
NYU Abu Dhabi

Abstract

Interactions between phytoplankton and bacteria arguably represent the most important inter- species association in aquatic environments. Phytoplankton are the major primary producers in the oceans and usually harbor phylogenetically distinct bacterial assemblages, essential for phytoplankton survival and ecosystem productivity. These microbial consortia occupy the microenvironment surrounding phytoplankton cells, known as the phycosphere. The phycosphere is physically sheltered and highly enriched in phytoplankton derived dissolved organic matter (DOM), whose remineralization by heterotrophic bacteria plays a major role in the carbon cycle and accounts for the transformation of ~20 Gt carbon per year in the ocean’s euphotic zone. Despite the importance of these symbioses, studying them is difficult due to (1) the minute size of the phycosphere, which makes it difficult to study these interactions in situ, and (2) the lack of model systems that are both environmentally relevant and tractable in the lab. In my talk, I will present recent findings from an emerging phytoplankton-bacteria model system that suggest unicellular eukaryotic phytoplankton can recruit and modulate microbial communities, similar to multicellular eukaryotes. In addition, I will show a new innovation in mass spectrometry that is allowing us to detect secreted metabolites from single phytoplankton cells directly in the phycosphere.