The Effect of Subtrate Availability on Cellulolytic Enzyme Production by Selected Wood-Rotting Microorganisms

Abstract

Extracellular cellulases have been produced in shake cultures of Polystictus ver8icolor, Fornes anno8U8, Lenzites trabea, Poria monticola, and Bacillus polymyxa, using substrates of cellulose powder and river birch woodmeal. The comparative effect on enzyme production of wet and dry ball milling of the substrates has been examined. Studies were also made to establish the relative amounts of enzyme diffused, bound, or adsorbed during production and the influence of pH on cellulase activity. It was found that wet ball milling reduces the particle size of both materials more rapidly than dry ball milling. There was an overall increase in enzyme released as the particle size of the substrate decreased, but no correlation was established between this phenomenon and growth of the microorganisms. Dry milled substrates of comparable particle size produced higher yields of cellulases than the wet milled substrates, Lenzites trabea being more active in enzyme production than any of the other organisms. Diffusion of cellulases occurred more readily in the brown rot fungi than in the two white rot microorganisms and a higher percentage of enzyme remained bound with the latter group.