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Cellulase and hemicellulase, both free and bound to cellulose, were produced in shake cultures of L. trabea and P. versicolor grown on ball-milled aspen (Populus tremuloides) or filter paper. Most of the enzyme was initially bound to cellulose plus mycelium and could not be readily dislodged, even by ultrasonic disintegration. Proportionally more enzyme could be obtained in the supernatant by reducing the cellulose concentration in the medium. No correlation was observed between the amount of growth and the amount of enzyme production. Rather, enzyme production was shown to be influenced by regulation of the growth rate through the use of cellulosic substrates of varying ease of accessibility and also when cultures were continuously supplied with glucose at a slow rate.

Phenethyl alcohol and some other specific solvents enhanced the production of cellulase by several fungi when added to culture growth media in minimal amounts. This solvent effect is considered to be cytoplasmic membrane-oriented. Cellulase synthesis possibly occurs in the same region of the cell.

Cellulase can be produced from growth in noncellulosic substrate if the growth rate of the producing organism is restricted. Phenethyl alcohol (PEA) is a growth inhibitor and was used to control the growth of M. verrucaria in attempts to obtain increased cellulase production. Cellulase yield was found to be increased without a restriction in growth rate when PEA was present in low concentrations (0.03% v/v). The effect was observed for other organisms but notably L. trabea, which produced considerable enzyme from a small quantity of mycelium. Here increased cellulase synthesis was concomitant with restricted growth. Other chemicals with PEA-like structure (e.g. benzyl alcohol) resulted in similar or more extensive cellulase synthesis. Of the substances tried, propyl alcohol was most effective, followed by acetone. PEA causes a swelling of cell walls and inhibits spore formation. This and other data given suggest that PEA affects the cytoplasmic membrane or the cell wall or both. Cellulase synthesis is considered to take place in the membrane and wall region of the cell.