Efficient saccharification of agave biomass using Aspergillus niger produced low-cost enzyme cocktail with hyperactive pectinase activity.

To develop a cost-effective, time-saving and efficient saccharification system for converting biomass into mono-/oligo-saccharides for production of bioethanol or other biochemicals, a relatively low recalcitrant and widely available biomass Agave americana was selected as feedstock. During the investigation of efficient enzyme cocktail, pectinase, which usually is neglect for biomass saccharification, was confirmed that it dramatically improves the saccharification of agave biomass. A production-friendly fungal strain of Aspergillus niger Gyx086 was employed for low-cost enzyme cocktails production using wheat straw as substance. The enzyme cocktail which was with hyperactive pectinase activity of 6.29 ±â€¯0.42 U/ml could efficiently saccharify un-pretreated agave biomasses. As a result, under a mild condition at 35 °C in less than 72 h, most of the polysaccharides were completely converted into reducing sugar. The low-cost, process-simplified, and efficient biotechnology should stimulate the development of agave as feedstock for green energy and bio-based products production.

Delignification overmatches hemicellulose removal for improving hydrolysis of wheat straw using the enzyme cocktail from Aspergillus niger.

Based on a general understanding that hemicellulose removal is more efficient than delignification for biomass deconstruction, an Aspergillus niger strain producing high xylanase activity was screened out from seventeen strains by clear halo experiments. Low-cost enzyme cocktail with high xylanase activity was produced from wheat straw medium fermented by the Gyx086 strain. The enzyme cocktail with high xylanase activity could more effectively hydrolyze wheat straw than other biomasses. However, only 30% of total carbohydrates could be hydrolyzed to reducing sugar in untreated wheat straw. Further enzymatic hydrolysis and pretreated trials were carried out, the results indicated that hemicellulose removal was less effective than delignification for de-recalcitrance of wheat straw and the crystallinity is little interference with the hydrolysis process. Delignified wheat straw was near-completely hydrolyzed by the enzyme cocktail in 60 h. This study advanced the knowledge in promoting wheat straw as feedstock for bio-based industry.