Technical Abstract: Thermobifida fusca was grown on cellulose (Solka-Flok), xylan, or corn fiber, and the supernatant extracellular enzymes were concentrated. SDS gels showed markedly different protein patterns for the three different carbon sources. Activity assays on a variety of synthetic and natural substrates showed major differences in the concentrated extracellular enzyme activities. These crude enzyme preparations were used to hydrolyze corn fiber, a low value biomass byproduct of the wet milling of corn. Approximately 180 mg of reducing sugar equivalents were produced per g of untreated corn fiber. When corn fiber was pretreated with alkaline hydrogen peroxide, up to 400 mg reducing sugars were released. Saccharification was enhanced by the addition of beta-glucosidase or by the addition of a crude xylanase preparation from the yeastlike fungus Aureobasidium.