Marine Biology Seminar: Dr. Laura Gómez-Consarnau (Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) & University of Southern California (USC))
"Light-harvesting in the surface ocean: the ecological role of proteorhodopsin-based photoheterotrophy"
Abstract: Sunlight drives virtually all life on the Earth’s surface, with about 50% of primary productivity occurring in marine systems. However, before the year 2000, all phototrophy in the ocean was thought to rely only on chlorophyll-like molecules. This traditional view of phototrophy changed radically with the discovery of marine bacterial proteorhodopsins (PR). Since then, PR genes and transcripts have repeatedly been found in extremely high abundances in all sunlit environments, particularly in the surface ocean. PRs are simple light driven proton pumps that allow microbes to transform light into chemical energy. My lab combines physiology studies, with (meta)-genomics, (meta)-transcriptomics and environmental quantifications to try to understand the role of light on PR-based photoheterotrophy in the ocean. In this talk I will show that the solar energy captured by PR-photoheterotrophy can promote bacterial growth, substrate uptake and survival to starvation under organic matter limitation. Also outside the prokaryotic domains, there is growing evidence that eukaryotic phytoplankton can produce PRs in response to nutrient limitation. I will further show the first quantitative field estimates of PR in different marine systems ranging from upwelling to HNLC areas.