Research

How do tiny cells shape the Earth System?

Differential activity of coexisting cells

There are 100,000 Prochlorococcus cells in every milliliter of surface water across Earth's vast open oceans making these cells the most abundant photosynthetic cell on the planet. We know these cells are incredibly diverse. They form distinct clades based on light, temperature, and nutrient acquisition strategies and exhibit extensive diversity in the leaves of the trees even between single cells. 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. This project is funded by 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 developing new model systems that combine picocyanobacteria and their predators, we aim to develop this missing side of marine microbiology - how cell dies and the evolutionary and ecological consequences of cell death.

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. Through NSF-OCE Award# 1830002 we are working 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.

Microbial Symbioses

Mucous grazers (gelatinous animals) of the ocean are suspected predators of microbes but they also host a diverse array of microbial taxa. For example, our work with pyrosomes shows complex microbial communities ranging from predatory microbes to unknown 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.