Proteomic allocation strategies observed through a micronutrient stress transition at the Antarctic sea ice edge

Scott McCain1, Andrew E Allen2, Alessandro Tagliabue3 and Erin Marie Bertrand1, (1)Dalhousie University, Department of Biology, Halifax, NS, Canada, (2)J. Craig Venter Institute, La Jolla, CA, United States, (3)University of Liverpool, Earth, Ocean and Ecological Sciences, Liverpool, United Kingdom
Microbes dynamically allocate their resources in response to environmental conditions, and how they allocate resources impacts organismal stoichiometry and therefore biogeochemistry. Despite increased modelling efforts to characterize how microbes allocate their proteins we have yet to systematically observe what these allocation strategies are in the ocean. We leveraged metagenomics and metatranscriptomics to characterize the metaproteome of a microbial community at the Antarctic sea ice edge through a micronutrient stress transition- micronutrient replete in the early growing season and micronutrient-limited in the later season. We then examine the in situ proteomic allocation of dominant phototrophic and heterotrophic taxa through this stress transition. Lastly, we couple these metaproteomic observations with a diatom proteomic allocation model to infer in situ growth rates. We propose this approach as a promising method for observationally determining growth rates of marine microbes in situ. Further, our study provides unique insights into how proteomic allocation strategies vary in trait-space.