Treatment time is an important process variable because large pro­cess footprints such as those required for this type of treatment require large amounts of land, and thus long treatment times can have a negative influence of the economics of the process, depending on land use require­ments (16). In addition, depending on the sensitivity of the treatment process to initial and transient conditions, widely variable product com­positions produced in time-sensitive degradation processes could have a large effect on the next step of the manufacturing process. Longer treat­ments gave progressively smaller gains in xylan removal and larger gains in glucan removal (Table 4). This observation is consistent with the fun­gus first utilizing the easily degraded hemicellulose and amorphous cel­lulose fractions, beginning with the hemicellulose.

In 4 wk, the maximum conversions observed were about 27% xylan and 19% glucan. At 8 wk, the maximum conversions observed were about 40% xylan and 34% glucan, while at 12 wk they were about 48% xylan and 41% glucan. At very low inoculum levels, the initial degradation (at 4 wk) was generally nonselective and thus primarily owing to indigenous organisms (Table 3). Above 10.9 mg of P. ostreatus/g of stems, the early degradation was much more selective for xylan vs glucan, indicating sig­nificant activity of the inoculated fungus. Maximum selectivities for xylan removal (ЛХ/AG) for inoculum levels exceeding 10.9 mg of P. ostreatus/g of stems were observed earlier in the treatments, with all moisture and inoculum combinations showing similar selectivities after 12 wk of treatment.