There are a total of 59 metabolites (6.67%) without a formula: __iCN900__fes_c, __iCN900__CLP_c, __iCN900__LIPID_c, __iCN900__malacp_c, __iCN900__RNA_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.

This model contains 735 unconserved metabolites: ahcys_c, xmp_c, gam6p_c, agm_c, alaala_c, ...

The list of unconserved metabolites is computed using the algorithm described in section 3.2 of "Detection of Stoichiometric Inconsistencies in Biomolecular Models." Bioinformatics 24, no. 19 (2008): 2245. doi: 10.1093/bioinformatics/btn425.