When Biologists and Modelers Meet in KBase: Case Example of Modeling Plant-Microbe Metabolic Interactions

Peatland ecosystems store vast amounts of terrestrial carbon as dead organic peat. The moss plant Sphagnum is a keystone genus in these nitrogen limiting peatland systems, highlighted by an important association with N2-fixing diazotrophic bacterial associates that may ultimately influence Nitrogen (N) and Carbon (C) cycling. However, the reports on the role of diazotroph N-fixation in supporting plant growth and maintaining the ecosystems as C-sinks rather than C-sources are inconsistent.

A modeling framework is needed to explore and understand this uncertainty surrounding N-fixation and N-cycling in such diazotrophic-plant interactions. Here we present one of the first full-scale stoichiometric models describing a simple metabolic interaction between the recently sequenced Sphagnum fallax and Anabaena spp., a representative cyanobacterium. We utilized the DOE Systems Biology Knowledgebase (kbase.us) to bring together experimental and computational results in developing the model. The data, the methods to analyze it, and the results are all accessible in a publicly available Narrative on KBase. We demonstrate how our stoichiometric model enabled us to explore the uncertainty surrounding the contribution of fixed N on Sphagnum biomass by formulating strong model predictions that can be tested experimentally.