Hydrolysis of Carboxymethyl Celluloses by Cellulases

Abstract

Water soluble carboxymethyl celluloses (CMCs) were hydrolysed using food grade commercial cellulases. The CMC hydrolysates obtained had low viscosity and contained mainly cellooligomers along with low amounts of cellobiose and glucose. A viscosity reduction of 98 to 99% was achieved after 5 min of cellulolytic hydrolysis of CMCs. On the other hand, acid hydrolysis of CMC was slow and took 1 h to reach a viscosity reduction of 93% and the hydrolysate contained high amounts of glucose in the reaction mixture. Cellulase from Trichoderma viridae produced two to four times more glucose in the CMC hydrolysate compared to cellulase from Aspergillus niger. Thus, the latter contained probably higher endo- and lower exo-β(1-4)- glucanase activity than the former. The amount of glucose in the reaction mixture was further monitored by optimizing various factors influencing the cellulolytic hydrolysis of CMCs, such as pH, temperature, time of reaction, substrate and enzyme concentration and type of CMC itself.