HYDROLYSIS AND TRANSFORMATION OF CELLULOSE WITH ASPERGILLUS-NIGER IBT-90 ENZYMES

Hydrolysis and transformation of Fibrenier cellulose (USA) with enzyme s from Aspergillus niger IBT-90 was studied. The process was performed at 50 degrees C and pH 4.8 for 24 h using an enzyme complex either as a properly diluted culture filtrate or as a mixture of isolated and p urified enzymes from A. niger IBT-90. In the latter experiments, enzym e-substrate ratios expressed as units of activity per 1 g of cellulose were as follows: endoglucanase E-1 and E-2, 40; beta-glucosidase, 40 and cellobiohydrolase, 2. Cellulose concentration was 5%. It was prove d that the crude cellulolytic complex from A. niger IBT-90 exhibits hi gher efficiency in the decomposition of cellulose in comparison to the mixture of enzymes isolated from this complex, as was revealed in ass ays of reducing sugars and determinations of light transmission throug hout cellulose fibres using a computer analysis of the microscopic ima ge. Comparison of both the endoglucanases E-1 and E-2 showed that the first enzyme is more active against cellulose. It liberated more reduc ing sugars and caused more significant decomposition of fibres. The pr edominant effect of the endoglucanase E-2 was a smoothing of the fibre surface. The cellobiohydrolase split a cellulose fibre into many shor t fibres.