Hydrolysis of sunflower seed meal lignocellulosic fraction by free and immobilized cellulases

Abstract

Lignocellulosic biomass is widely abundant in nature and recognized as
potential renewable energy source. Its efficient transformation into bio-based
fuels is enabled only after adequate pretreatment, followed by enzymatic
sacharification and microbial fermentation. Hereby we present application of two
cellulase preparations – from Aspergillus niger and Trichoderma reesei (Celluclast®)
in treating sunflower seed meal lignocellulosic fraction (SSMLF). Temperature and
pH optimums of two enzymes were determined – 52 °C and pH4.8 for A. niger
cellulase and 55 °C and pH4.5 for Celluclast®. At optimized conditions, milled
SSMLF was hydrolyzed by both biocatalysts. With A. niger cellulase higher initial
reaction rates were accomplished and yield of 70 mM glucose equivalent was
obtained with 6 % (w/v) of enzyme after 6 hours. On the other hand, application
of Celluclast® led to lower initial reaction rates and yielded 25 mM of glucose
equivalent with 10 % (v/v) of enzyme. To ensure cost-effective application of
A. niger cellulase, the possibility of its immobilization on different supports was
investigated. By using porous methacrylate-based carrier with C6 spacer arm and
primary amino groups – LifetechTM ECR8409, preparation with highest activity was
produced. This preparation was successfully applied in saccharification of SSMLF
and showed unchanged catalytic efficiency comparing to free enzyme.