Increased Saccharification Yield by Cellulases Coupling

In many cellulase preparations the enzymatic activity is not well balanced and the catalytic attack of the cellulose is limited. The purpose of this study was to investigate the possibility of simultaneously using two cellulases from distinct sources for improving the rate of hydrolysis as alternative to other costly techniques which require enzyme separation and purification A comparative study on the hydrolysis of microcrystalline cellulose (Avicel), amorphous cellulose derivative (CMC) and native cellulose-olive husks, catalyzed by mixtures of cellulase complexes was performed in ultrafiltration and batch reactors. The experiments were carried out varying the percentages of Trickoderma viride and Aspergillus niger in the enzymatic preparation and the effect of enzyme composition on cellulose conversion and glucose selectivity was determined. The use of mixtures of these two enzymes improves cellulose saccharification in a different extent depending on the chemical and physical features of the cellulose and on the biomass particle size. The increase of glucose production is three times as big as with the use of the two enzymes separately. For the olive husks the optimum is attained for a T. viride to A. niger ratio of 2:1. An ultrafiltration-membrane reactor for the hydrolysis of the three substrates can be helpfully adopted since product inhibition is controlled and a higher glucose selectivity is reached in comparison With batch ones.