An isolate of the fungus Penicillium janthinellum that produces large amounts of xylanase with no detectable cellulase activity was used as a model system to study enzyme induction and production and to illustrate the use of such preparations in the recovery of cellulosic textile fibers. For large-scale production of xylanase, the hemicellulosic fraction from steam-exploded sugar cane bagasse (SEB(h)) was investigated as an abundant and efficient inducer. A two-step cultivation system, in which mycelia were first produced under noninducing conditions and switched to inductive media, demonstrated that xylanase production was dependent on the noninducing carbon source. A consistent decrease in lag periods prior to xylanase detection, as well as a sharp increase of production rates with length of starvation by noninduced cells, suggested that xylanase synthesis only started after intracellular reserves were depleted. These results suggest that plants used to produce textile fibers are potential targets for enzymatic treatments by xylanase-producing organisms