for dfba_obj_rxn in list(submodel.dfba_obj.expression.dfba_obj_reactions):
                            submodel.dfba_obj.expression.dfba_obj_reactions.remove(dfba_obj_rxn)
                            objs_for_merged_dfba_expression[DfbaObjReaction][dfba_obj_rxn.id] = dfba_obj_rxn