
Full text loading...
Carboxymethylcellulose was used as a model substrate in batch and continuous cultures in a study of cellulose metabolism and the synthesis of β-glucosidase and endoglucanase by Trichoderma koningii. The maximum growth rate on CM-cellulose compared favourably with that on cellulose. In batch cultures mycelial inoculum was more effective than spore inoculum in initiating synthesis of both enzymes. Synthesis of β-glucosidase in larger amounts than the maximum provided by growth from the initial mycelial inoculum was achieved by encouraging renewed growth by replenishing half the spent medium when the carbohydrate had been consumed: the same treatment failed to enhance the yield of endoglucanase. Growth from a spore inoculum gave considerably lower yields of β-glucosidase but ultimately doubled that of the endoglucanase. The delayed synthesis of endoglucanase was also overcome and its yield increased up to fourfold by restricted aeration, whereas that of β-glucosidase was unaffected. Maximum synthesis of both enzymes was obtained simultaneously in continuous culture together with improved yields. The nature of the hydrolysis of cellulose and the effect of its products, cellobiose and glucose, are considered in relation to the synthesis of β-glucosidase and the endoglucanase.