Production of Cellulases by Aspergillus sp. GDX02 in a Solid-State Fermentation Using Oil Palm Empty Fruit Bunch

Abstract

A reduction in enzyme cost is one of the important factors for making bioethanol production more economically feasible. To this aim, we isolated a fungus, GDX02, to produce cellulases using agricultural wastes, including empty fruit bunch (EFB), under solid-state fermentation (SSF). This study was conducted to determine the best substrate and optimal fermentation conditions for maximum cellulase production using GDX02. Of the different substrates tested, rice straw resulted in the highest enzyme production. As a nitrogen source, a supplement of yeast extract was necessary to achieve high enzyme activity. In particular, FPase activity reached its maximum at a supplement of 7 % yeast extract, whereas β-glucosidase activity experienced little change under all concentrations of yeast extract tested. The GDX02 produced high FPase and β-glucosidase after three-day culture of EFB at 40 % moisture level. The saccharification yield of pretreated EFB by GDX02 cellulase was comparable to that from the commercial enzymes Celluclast and C-Tec2, indicating the great potential use of GDX02 cellulase for cellulosic ethanol production from EFB.