Straw stems were first treated for 6 wk in small columns with P. ostreatus at 40 mg of P. ostreatus/g of stems and 1.6 g of H2O/g of dry stems, as described. These stems were then inoculated 1:10 into fresh stems, the moisture content was adjusted to 1.6 g of H2O/g of dry stems, and the mixture was added to the drums for treatment. Because of the large amount of nitrogen-limited inoculum needed for the initial small-column step, the nitrogen-limited inoculum was produced in a slightly different manner than described above. This mycelial inoculum was produced at Utah State University as previously, but the mycelia from the maintenance slants were transferred directly into the nitrogen-limited medium without first being enriched in YM broth. Thus, both of the enrichment steps in the preparation of this mycelial inoculum were carried out in the nitrogen-limited medium. The fungal pellets produced in this manner were harvested as before, shipped under refrigeration to the INEEL, and stored at 4°C until use (up to 4 wk).

After 6 wk the treated stems were removed from the glass columns and mixed by hand at 1:10 (w/w) with fresh, air-dried, uninoculated straw stems. Random samples of the 6-wk-degraded stems were dried, ground to 60 mesh, and analyzed for composition as described under Composi­tional Analyses. While it was not known how much inoculum would be necessary for the altered inoculation method, a 10 wt% inoculation of wood chips containing an active culture of the desired white-rot fungus has been successful in soil bioremediation (10). The moisture content was brought to 1.60 g of H2O/g of stems by spraying distilled water with a pressurized garden sprayer onto the fresh stems as they were mixed with the treated straw from the glass columns. The inoculated stems were then packed into 208.5-L drums at about 7.5 kg dry wt of inoculated straw per drum. Before loading the drums, a 56-cm-diameter perforated steel disk was placed in the bottom of each drum and elevated to about 5.7 cm above the bottom of the drum using screws. Humidified oil-free instrument air at 127.6 kPa was supplied at 400-500 mL/min to the bottom of each drum beneath the perforated disk; the pressure drop over each drum was about 41.4 kPa. The air exited the system separately through the centers of the lids of each drum through in-line 16-cm2 Whatman HEPA-Vent Filters with a porosity of 0.3 |im (Whatman, Newton, MA). After 6 or 12 wk of treatment, the drums were opened and several samples were removed from various locations within the straw beds. The samples were dried, ground to 60 mesh, and analyzed for composition as described under Compositional Analyses. The drums were then resealed and shipped to the Wood Mate­rials and Engineering Laboratory at WSU for analyses of various compos­ite formulations and extrusion testing. Untreated straw was also sent to WSU for these analyses. For the composite testing, the straw samples were referred to as Neat (untreated), Degrade1 (treated for 6 wk), and Degrade2 (treated for 12 wk).