The Terrafors-IS bioreactor works well for in situ sterilizable, laboratory-scale fermentation of solids and semi-solids. It provides aseptic conditions through automatic steam sterilization of a rotating drum. Maximal working volumes include 3–4 kg of solids, semi-solids, or up to 7 L of liquids. Two ports on the top plate are included for substrate addition/removal and sampling. The automatic in situ sterilization system uses direct steam injection with a maximum temperature of 134°C. The use of steam for sterilization is suited for production of pharmaceuticals and also allows a “one-vessel” solution for fungal substrate bioconversion followed by microbial fermentation.