Fig. 1

Toy model. A Example of a metabolic reaction. Reactants and products are depicted as circles and reactions as rectangles, respectively. Reaction directionality is indicated by the arrows. B Three functional reactomes derived from the toy model, each capable of synthesizing the biomass compounds M10_i, M11_i, and M12_i from the environmental precursors (‘MX_e’ compounds depicted with green circles). C Pan-reactome network aggregates reactions from the different reactomes into a single network. The “_e” and “_i” termination of metabolites denote external and internal metabolites, respectively. D An example of a panEFM. Each reaction in this network is essential since its removal would impair the synthesis of the biomass components. E Collection of all nine possible panEFMs that can be created from the reactions in this toy pan-reactome in a rich environment. Dark squares denote the presence of reactions. The frequency of reactions across the collection of panEFMs is shown in the last row