Title
Pretreatment and enzymatic hydrolysis of pearl millet stover by multi-enzymes from Aspergillus nidulans AKB-25
Authors
AMIT KUMAR DHARM DUTT and ARCHANA GAUTAM

Received January 13, 2015
Published Volume 50 Issue 7-8 July-August
Keywords pearl millet stover, alkali pretreatment, saccharification, enzymes, Aspergillus nidulans, surfactants

Abstract
The pretreatment of pearl millet stover at 3% alkali dose was found to yield 65.85% cellulose, 19.35% hemicelluloses and 9.78% lignin with substantial reduction in extractives (92.5%) and proteins (84.1%). Alkali treatment enhanced the Brunauer-Emmett-Teller (BET) surface area and water retention value (WRV) by 322.92 and 78.66%, respectively, compared to the untreated sample.The crystallinity index was increased with increasing alkali doses and reached the maximum, i.e.41.78%,at 3% alkali treatment, compared to the untreated pearl millet stover (27.40%). Likewise, conversion of biomass into reducing sugars increased with increasing alkali doses up to 3% and the yield of reducing sugars was 53.13% at a hydrolysis time of 72 h. An enzyme dose of 15 FPU/g dry substrate was found to produce maximum reducing sugars (57.77%) after 72 h of enzymatic hydrolysis. The addition of Tween-20 and Tween-80 (0.15 g/g dry substrate) increased saccharification yield up to 62.14 and 64.77%, respectively, compared to the control (57.64%).