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Comparing reported water holding capacities for microbial cellulose is difficult because different methods are used. The different methods affect both the average value and the precision. In this new method, a vacuum of 10 mm H2O (98 Pa) is applied to the wet cellulose to stabilize the sample prior to determining the wet weight. This simple method lowers the standard deviation by 50% or more over other methods.

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The effect of fungal inoculum properties on colonization of nonsterile soil by three isolates of the white-rot fungus Trametes versicolor was investigated. Fungal inoculum properties were examined in separate experiments and were fungal inoculum composition, age of fungal inoculum, concentration of the inoculum and inoculation method. The fungal inoculum composition study compared pine versus poplar sawdust as the basic carrier with varying amounts of corn grit, corn meal and starch. The age of the fungal inoculum studied ranged from 3 to 21 days. The inoculum concentration gradually increased from 0 to 50% (v/v). The study assessing inoculation method compared mixing with layering techniques. The effect of moisture conditions of soil, sawdust and sand in combination with two inoculation methods (mixing versus point source inoculation) on colonization by T. versicolor was also determined. Colonization of soil was always assessed visually and enzymatically monitoring mycelial growth, biological potential (fluorescein diacetate assay) and laccase levels. Generally, the three different assessment methods correlated (P < 0.05) with each other. A fungal inoculum based on pine sawdust supported white-rot fungal growth in soil better than a poplar sawdust basis. Colonization of soil by T. versicolor was improved by increasing the corn content of the fungal inoculum. Younger (<7 days old) fungal inoculum resulted in better soil colonization than older (>10 days). A strong correlation (P < 0.001) was observed between the amount of fungal inoculum used in the soil augmentation and white-rot fungal colonization of soil. Inoculation of the fungal inoculum into soil by mixing was preferable over application in layers or point source inoculation. Moisture level did not influence biological potential measurements, but affected mycelial growth and laccase expression.

Mass and energy balances were performed on a compost biofilter to identify the mechanisms for water content change in the compost bed material. Three mechanisms were identified: humidity fluctuations at the inlet and outlet, heat generation from microbial oxidation, and gradients in the water potential. Microbial oxidation and humidity fluctuations were the dominant mechanisms for water content changes. Time domain reflectometry was used to estimate on-line volumetric water content in the bed material. Biofiltration experiments demonstrated a moving front of temperature increase and water evaporation associated with the microbial oxidation of toluene. The localized microbial heat generation evaporated sufficient water from consecutive sections of the bed, eventually impairing degradation throughout the entire column.

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