Alexander Bradley, Ph.D.

Assistant Professor, Washington University in St. LouisAlexander Bradley’s website

ECIMMEE Project: Investigating Biogeochemical Consequences of Metabolic Heterogeneity in Marine Microbial Carbon Degradation

Individual microbial cells catalyze chemical reactions that both sustain their metabolism and change their environment. These reactions happen quickly and at small spatial scales. The cumulative effects of these reactions happen slowly and on large spatial scales and result in the emergence of structured microbial ecosystems and global biogeochemical cycles. A key challenge of microbial ecology is to understand how the principles that affect the small and fast scales produce the consequences that we see at the slow and large scales. This project will address one aspect of this challenge by trying to understand the principles that govern heterogeneity in metabolism of individual cells in a population. For example, do all cells in a given environment and descending from the same ancestor perform the same metabolism? Or do some cells specialize and undertake a rare metabolism that catalyzes an unusual reaction or relies on byproducts of the bulk population? This work will address these questions using isotope tracers in conjunction with microscale secondary ion mass spectrometry (SIMS). This approach is capable of examining the elemental and isotopic composition of hundreds of individual cells from a microbial population. The results will inform our understanding of how to interpret tracers of population-level metabolism, ranging from various ’omics techniques to isotopic fractionations.

Alex Bradley is an associate professor in the Department of Earth and Planetary Sciences at Washington University in St. Louis. His research combines field and laboratory investigations to examine a wide range of problems in biogeochemistry. He is interested in understanding the principles that govern the function and evolution of microbial ecosystems over the course of Earth’s history. His laboratory explores how biogeochemical information is preserved in sedimentary environments over a wide range of time scales, with a focus on molecular structures and isotopic signatures. Before joining the faculty at Washington University, Alex was a postdoctoral fellow at Harvard University. He received his A.B. in earth and planetary sciences from Harvard University and a Ph.D. in geochemistry from the Massachusetts Institute of Technology.

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