“The true biologist deals with life, with teeming boisterous life, and learns something from it, learns that the first rule of life is living.” – John Steinbeck, “Log From The Sea of Cortez

We are broadly fascinated by the microbial world, with a particular focus on the role that microbes play in the oceans. We use model systems to decipher the mechanisms through which cells respond to interactions with other organisms, and explore how these interactions contribute to emergent community behaviors. We ask questions across scales from individual cells to global ecosystems, integrating concepts and approaches from microbiology, genomics and computational biology, ecology, cell biology, microbial physiology, systems biology, and oceanography. 

While we love all bacteria, we have a special place in our hearts for the marine cyanobacterium Prochlorococcus– the smallest and most abundant photosynthetic organism on the planet. We utilize Prochlorococcus as a model to help us uncover principles broadly applicable to understanding microbial systems.

Extracellular Vesicles

Extracellular vesicles are tiny (~100nm diameter) particles released by most, if not all, organisms on Earth. Vesicles can transport a variety of proteins, DNA, and metabolites between cells, suggesting that they play important roles in mediating microbial interactions. We have identified vesicles as a new and abundant component of marine ecosystems, and are working to understand their functions. The lab is currently addressing an array of questions concerning vesicle-mediated interaction dynamics and intercellular delivery, horizontal gene transfer, food web interactions, and more!

Current projects include:

  • Measuring the contributions of vesicles to marine dissolved organic carbon cycling
  • Examining the genetic content of vesicles and their role in horizontal gene transfer
  • Defining the nature of vesicle-mediated interaction networks
  • Exploring vesicle-virus interactions

Impacts of co-culture on Prochlorococcus

Organisms evolve in the context of complex communities, yet most of our understanding of genetics and cellular physiology is derived from studies of species in isolation. Experiments on isolated organisms do not reflect how they will behave in more ‘natural’ conditions, where they experience a complex physical and chemical environment, are surrounded by other organisms, and as such function as part of a self-organizing, adaptive living system. We use defined laboratory co-cultures to uncover new ways through which microbes interact with one another, how those interactions impact cellular physiology, and reveal clues about the co-evolution of these systems. We are currently working to better understand how heterotroph interactions shape diel gene expression in Prochlorococcus and allow these cells to withstand stress conditions.

Microbiology of the Deep Ocean

Through collaborations, we have a growing interest in different aspects of the microbes that live in the vast aphotic zone, including:

  • Understanding how cyanobacteria can survive in the dark
  • Exploring microbial diversity of deep ocean seamounts, coral ecosystems
  • Addressing questions of community function in the mesoplegaic through analysis of single cell genomes
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