So, you're saying that some other contaminant is in the inulin? What might that be, for such effects?
It's one of the few things out there not made from a fermentation process by Aspergillus, so it can't be yeast. HOWEVER, do note that lots of things are made FROM INULIN by Aspergillus fermentation, so that sort of answers the "can yeast eat inulin" question...