Pretreatment of Agricultural Wastes for the Production of Cellulolytic Enzymes from Aspergillus niger 386017M1 by Solid State Fermentation

Abstract

Suitable pretreatments of rough rice bran (RRB), palm kernel meal (PKM) and cassava pulp (CP) containing lignocellulose were investigated as feedstocks for the production of cellulolytic enzymes from Aspergillus niger 386017M1 by solid state fermentation (SSF). The suitable steam-pretreated RRB yielded maximum cellobiohydrolase (CBH) and β-glucosidase (BG) activities of 6,244 and 28,485 units.g-1 (dry solid), respectively. Additionally, the steam-pretreated PKM yielded maximum CBH and BG activities of 1,626 and 26,869 units.g-1, respectively. The acid-pretreated CP yielded CBH and BG activities of 7,303 and 9,349 units.g-1, respectively. The maximum growth of A. niger from either the untreated or pretreated samples was 3–5 d at a pH of 4–5 and no spores were detected. The lignin contents of steam-pretreated PKM and acid-pretreated CP were reduced 1.4 and 1.3 fold, respectively, compared to the control; the cellulose contents increased 3.2 and 1.6 fold, respectively, and the CBH activities increased 135–163 and 453–698 fold, respectively. For steam-pretreated RRB, the 1.5-fold lignin reduction and 2.0-fold cellulose increase did not affect CBH production. These fi ndings are encouraging for the production of high value added products such as enzymes that are used in both the food and feed industries.