In the Borer Lab, we combine experimental approaches with field-going campaigns andcomputational modeling to interrogate microbial life at the scale that matters to individual cellsand predict how they collectively govern biogeochemical processes in the Earth system.
Particle-microbe interactions
Sinking marine particles in the ocean are localized hotspots of nutrients and elevated microbial activity. However, getting onto these sinking particles is daunting. While particles sink relatively slowly in human terms (tens of meters per day), this is rapid relative to the bacterial swimming velocity. Translated to our scale, a particle settling at 100 meters per day is like jumping onto a train at more than 100 miles per hour! As such, interactions with sinking particles are restricted to infrequent particle encounters, occur in split seconds when the particle and bacterial cells are proximal, and are governed by the microscale physics of the particle’s boundary layer. Marine bacteria are formidably adapted to cope with these challenging conditions. We explore the diverse strategies and evolutionary traits of particle-associated and free-living microbes in the ocean to understand how these impact ecosystem functioning and harness them for possible bioengineering applications.
Localized biogeochemistry
Microbes have the power to transform ecosystems by sheer number alone. Similar to how humans live in cities, microbes aggregate in hotspots such as the rhizosphere in soil, biofilms in sediments and porous media, and on marine particles or the phycosphere (mucus layer around phytoplankton) in the oceans. Their elevated metabolic activity impacts the localized biogeochemistry: from acidifying through the release of intermediate metabolites, the creation of anoxic hotspots due to the rapid consumption of oxygen, and metabolic interactions with other species through resource sharing. While an individual hotspot does not impact global biogeochemistry, they do collectively. One liter of seawater may contain thousands of particles harboring millions of microorganisms. By interrogating the biogeochemistry and microbial
communities of an individual particle, we can infer biogeochemical rates and ecosystem processes by integrating across all particles, ultimately establishing mechanistic links between the metabolic activity of individual microbes and global biogeochemistry.