Predicting Biological Information Flow in a Model Oxygen Minimum Zone
Stilianos Louca1, Alyse Kathleen Hawley2, Sergei Katsev3, Monica Torres Beltran2, Maya P Bhatia2, Celine Michiels2, David Capelle4, Gaute Lavik5, Michael Doebeli6, Sean Crowe7 and Steven James Hallam7, (1)University of British Columbia, Institute of Applied Mathematics, Vancouver, BC, Canada, (2)University of British Columbia, Microbiology & Immunology, Vancouver, BC, Canada, (3)University of Minnesota Duluth, Duluth, MN, United States, (4)University of Manitoba, Centre for Earth Observation Science, Winnipeg, MB, Canada, (5)Max Planck Institute for Marine Microbiology (MPI), Bremen, Germany, (6)University of British Columbia, (7)University of British Columbia, Vancouver, BC, Canada
Abstract:
Microbial activity drives marine biochemical fluxes and nutrient cycling at global scales. Geochemical measurements as well as molecular techniques such as metagenomics, metatranscriptomics and metaproteomics provide great insight into microbial activity. However, an integration of molecular and geochemical data into mechanistic biogeochemical models is still lacking. Recent work suggests that microbial metabolic pathways are, at the ecosystem level, strongly shaped by stoichiometric and energetic constraints. Hence, models rooted in fluxes of matter and energy may yield a holistic understanding of biogeochemistry. Furthermore, such pathway-centric models would allow a direct consolidation with meta'omic data.
Here we present a pathway-centric biogeochemical model for the seasonal oxygen minimum zone in Saanich Inlet, a fjord off the coast of Vancouver Island. The model considers key dissimilatory nitrogen and sulfur fluxes, as well as the population dynamics of the genes that mediate them. By assuming a direct translation of biocatalyzed energy fluxes to biosynthesis rates, we make predictions about the distribution and activity of the corresponding genes. A comparison of the model to molecular measurements indicates that the model explains observed DNA, RNA, protein and cell depth profiles. This suggests that microbial activity in marine ecosystems such as oxygen minimum zones is well described by DNA abundance, which, in conjunction with geochemical constraints, determines pathway expression and process rates. Our work further demonstrates how meta'omic data can be mechanistically linked to environmental redox conditions and biogeochemical processes.
