Research

How do tiny cells shape the Earth System?

Microbial Symbioses

Our research has examined many types of symbioses including defining partners in an important nitrogen-fixing symbiont-turned-organelle relationship and learning how two different microorganisms can gain resilience through their coupled metabolisms. At a larger scale, we have examined symbioses between microbes and zooplankton. For example, our work with salps and pyrosomes shows complex microbial communities ranging from novel taxa to agents of bioluminescence. Through the Aquatic Symbioses Genomics Project, we are a part of a collaborative research hub with researchers around the world analyzing the genomes of these animal hosts and their microbes to discover the evolution and function of these partnerships.

Great Lakes Cyanobacteria

Picocyanobacteria form the base of the food web in the Great Lakes. As in marine environments, these Great Lake picocyanobacterial populations are genetically diverse and occupy a range of distinct environments across lakes and depths. We worked with the Coleman Lab at the University of Chicago to connect picocyanobacterial genotypes and phenotypes in the Great Lakes towards better understanding of how these populations shift with environmental change. Specifically, we will be applying our 5-laser flow cytometry technique to distinguish coexisting Synechococcus populations based on their pigments. (NSF-OCE Award# 1830002)

Differential activity of coexisting cells

There are 100,000 Prochlorococcus cells in every milliliter of surface water and they are incredibly diverse. One major unanswered question is: Do coexisting Prochlorococcus of distinct genetic lineages contribute equally to primary productivity in the microbial community? Through oceanographic field studies and laboratory work with cultivated isolates our research group aims to understand how small differences in genome sequences allow these cells to contribute to nutrient and energy cycles on global scales in different ways (NSF-OCE #1646709).

Microbes as prey

Picocyanobacteria population sizes are remarkably stable. Each day, cell division is balanced with mortality. Predators include viruses, protists, and some large filter-feeding zooplankton. However, there is so much more to be learned of their grazing rates, selectivity, and the nature of their evolutionary pressure on picocyanobacteria and how much this matters to global processes. Through collaboration with the Sutherland Lab and through developing new model systems that combine picocyanobacteria and their predators, we aim to develop this missing side of marine microbiology. How do cells die and what are the evolutionary and ecological consequences of cell death? (NSF-OCE #2419057, 1851412).