I wanted to perform a functional analysis of my predicted ORFs of a metagenome. Using BlastKOALA I managed to assign KEGG ORthologies to my ORFs and used Pathway reconstruct to categorise the predicted functions. However, I noticed that many ORFs that are assigned to a KO number, doen't appear in any of the functional categories of KEGG Pathways. These functions comprise several antibiotic resistances for sulfonamide (Sul1), mercury (MerE) and tetracycline (TetA). Does somebody know why many proteins are assigned a KO number, but do not end up in any of the functional categorie? Thank you for your help!