A total of 78 (3.96%) metabolites are not produced by any reaction of the model: __iECx55__apoACP_c, __iECx55__ag_c, __iECx55__trnaala_c, __iECx55__alpp_p, __iECx55__ap5a_c, ...

Orphans are metabolites that are only consumed but not produced by reactions in the model. They may indicate the presence of network and knowledge gaps. Implementation: Find orphan metabolites structurally by considering only reaction equations and bounds. FBA is not carried out.

There are a total of 1858 metabolites (94.31%) without a formula: __iECx55__pcresol_c, __iECx55__5drib_c, __iECx55__aacald_c, __iECx55__amob_c, __iECx55__mththf_c, ...

To be able to ensure that reactions are mass-balanced, all model metabolites ought to be provided with a chemical formula. Since it may be difficult to obtain formulas for certain metabolites this test serves as a mere report. Models can still be stoichiometrically consistent even when chemical formulas are not defined for each metabolite. Implementation: Check if each cobra.Metabolite has a non-empty "formula" attribute. This attribute is set by the parser if there is an fbc:chemicalFormula attribute for the corresponding species in the SBML.