Olivia Ahern, a postdoctoral scientist at the Marine Biological Laboratory (MBL), was recently named an awardee of the Joint Genome Institute’s (JGI) Community Science Program (CSP) for her research proposal to illuminate microbial food web connectivity. Through this award, JGI will provide in-depth DNA and RNA sequencing services to Ahern and her collaborators, along with expert advice. 

Ahern and the co-principal investigators on the project, Joseph Vallino (MBL senior scientist) and Julie Huber (Woods Hole Oceanographic Institution senior scientist), are currently investigating the structure of microbial food webs by tracking organic carbon (i.e., food) incorporation into bacteria, as well as their predators, by labeling the organic carbon with stable isotopes of carbon. As the labeled carbon is consumed, it becomes incorporated into the RNA and DNA of the microbes. Using a powerful technique called stable isotope probing, Ahern, in collaboration with Huber, can identify which bacteria consume the labeled carbon sources, and which predators are consuming the bacteria. From this information, the team can determine if microbial foods webs are highly interconnected or sparsely connected, which has important implications for their stability and functioning.

Bioreactors containing complex microbial communities from Sider’s Pond in Falmouth, Mass., spiked with carbon stable isotopes. Credit: Joe Vallino

The CSP award establishes a collaboration with JGI to develop high-quality metagenomes and metatranscriptomes from samples taken from the teams’ experiments. This new genomic information will greatly facilitate identification of the prokaryotic primary consumers in microbial food webs, how organic carbon exchanges between the bacteria, and reveal eukaryotic community composition and viral dynamics. The sequencing information provided by the award will also be used to construct metabolic models from metagenomic assembled genomes.

The JGI award augments an existing award from the National Science Foundation to Vallino and Huber to investigate microbial food webs. The new award will support exploration of a variety of questions at the intersection of microbial ecology, biogeochemistry, and ecological modeling.