A Microbe’s Perspective on the Marine Nitrogen Budget

EAPS News
Tuesday, May 14, 2019

Babbin Selected for 2019 Simons Early Career Investigators in Marine Microbial Ecology and Evolution Award.

The following news article is adapted from a press release issued by the Simons Foundation.

The Simons Foundation has named nine scientists as 2019 Simons Early Career Investigators in Marine Microbial Ecology and Evolution (ECIMMEE); among them is Andrew Babbin, EAPS Doherty Assistant Professor in Ocean Utilization. The three-year awards are intended to help launch the careers of outstanding investigators in this area.

Babbin will be investigating the availability of fixed nitrogen, predominantly in the forms of ammonium and nitrate. This fixed nitrogen limits primary production across much of the global oceans. The standing stock of this bioavailable pool is in turn regulated by the balance of marine microorganisms producing ammonium from dinitrogen gas (diazotrophy) and reforming dinitrogen from nitrate and nitrite (denitrification). Strikingly, the specific factors regulating the rates and efficiency of nitrogen transformation processes remain poorly constrained.

His group will work to unravel the complexities of the microbial nitrogen cycle to better understand the mechanisms by which these climatically critical bacteria reshape the chemical environment for themselves and for all marine organisms. The laboratory system utilizes exquisitely controlled chemical and microbial compositions, seeding microbes into novel droplet-based microfluidic incubators. By integrating both environmental isolates and genetically modified mutants, the Babbin team will systematically determine the range of conditions under which each nitrogen metabolic transformation can occur. Complementary chemostat experiments will extend the parameters extracted from the droplet-based batch cultures to real-world climate simulations and metabolic models. This approach to empirically and theoretically constrain the kinetic and thermodynamic characteristics of each nitrogen transformation step will enable a mechanistic framework of community nitrogen metabolism and species interactions. Through these targeted experiments and analyses, we will connect metabolic activities at the micro-scale to global nitrogen biogeochemistry.

Other awardees include: Frank Aylward of the Virginia Polytechnic Institute and State University, Roxanne Beinart of the Graduate School of Oceanography at the University of Rhode Island, Alexander Bradley of the Washington University in St. Louis, Randelle Bundy of the University of Washington, Kristen Hunter-Cevera, a Hibbitt Early Career Fellow at the Marine Biological Laboratory, William Leavitt of Dartmouth College, Jeffrey Morris of the University of Alabama at Birmingham, and Xinning Zhang of Princeton University.