Four enzyme preparations produced by fungal species belonging to different genera (Aspergillus niger, Corynascus sp., Penicillium verruculosum, Trichoderma reesei) were used for synthesis of disaccharides by D-glucose (60% w/v) condensation catalyzed by -glucosidase.Effects of pH and temperature on the disaccharide synthesis were studied, and glycoside linkage patterns for enzymes from different sources were determined.The highest concentration of disaccharides (114 and 118 g/l) was achieved in the case of A. niger and Corynascus sp. enzymes after 48 h of the condensation reaction carried out at 70 o C and optimal pH; the P. verruculosum sample slightly conceded them in the yield of products (96 g/l), while the T. reesei preparation displayed the lowest synthetic activity (35 g/l).Gentiobiose was predominantly formed in the reaction catalyzed by the first three enzyme samples, while in the case of T. reesei laminaribiose was the main condensation product.

An extremely highly active cellobiohydrolase (CBH IIb or Cel6B) was isolated from Chrysosporium lucknowense UV18‐25 culture filtrate. The CBH IIb demonstrated the highest ability for a deep degradation of crystalline cellulose amongst a few cellobiohydrolases tested, including C . lucknowense CBH Ia, Ib, IIa, and Trichoderma reesei CBH I and II. Using purified C . lucknowense enzymes (CBH Ia, Ib, and IIb; endoglucanases II and V; β‐glucosidase, xylanase II), artificial multienzyme mixtures were reconstituted, displaying an extremely high performance in a conversion of different cellulosic substrates (Avicel, cotton, pretreated Douglas fir wood) to glucose. These mixtures were much or notably more effective in hydrolysis of the cellulosic substrates than the crude multienzyme C . lucknowense preparation and other crude cellulase samples produced by T . reesei and Penicillium verruculosum . Highly active cellulases are a key factor in bioconversion of plant lignocellulosic biomass to ethanol as an alternative to fossil fuels. Biotechnol. Bioeng. 2007; 97: 1028–1038. © 2007 Wiley Periodicals, Inc.

Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delig-nification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBCl and MSUBC2) and two commercial cellulase preparations (TRl and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBCI showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBCI achieved> 76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (~ 44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without B-glucosidase supplementation.

Seven cellulase preparations from Penicillium and Trichoderma spp. were evaluated for their ability to hydrolyze the cellulose fraction of hardwoods (yellow poplar and red maple) pretreated by organosolv extraction, as well as model cellulosic substrates such as filter paper. There was no significant correlation among hydrolytic performance on pretreated hardwood, based on glucose release, and filter paper activity. However, performance on pretreated hardwood showed significant correlations to the levels of endogenous β-glucosidase and xylanase activities in the cellulase preparation. Accordingly, differences in performance were reduced or eliminated following supplementation with a crude β-glucosidase preparation containing both activities. These results complement a previous investigation using softwoods pretreated by either organosolv extraction or steam explosion. Cellulase preparations that performed best on hardwood also showed superior performance on the softwood substrates.

Seven fungal cellulase preparations from Trichoderma and Penicillium spp. were evaluated for their ability to hydrolyze the cellulose component of lignocellulose samples prepared from softwoods by steam explosion or organosolv pretreatment. Hydrolysis was quantified using two indices: mean specific rate and specific conversion. The activities of the cellulase preparations on model cellulosic substrates (filter paper, carboxymethylcellulose and Avicel) were also determined, together with their β-glucosidase, xylanase, pectinase, galactomannanase and β-glucanase activities. The ability of a cellulase preparation to hydrolyze pretreated softwood showed little correlation with its activity on filter paper, carboxymethylcellulose and Avicel; however, there was a significant correlation with its level of endogenous β-glucosidase and xylanase activity. Differences in the performance of the various cellulase preparations were substantially reduced following supplementation with a commercial β-glucosidase preparation from Aspergillus niger. In addition to β-glucosidase, this preparation was shown to contain significant levels of endogenous xylanase activity. It appears that the levels of endogenous β-glucosidase and xylanase are important factors in determining the ability of a cellulase preparation to hydrolyze pretreated softwood and that deficiencies in the levels of both enzymes can be compensated by supplementation with corresponding activities present in the β-glucosidase preparation. Presumably, β-glucosidase improves cellulose hydrolysis by reducing end-product inhibition by cellobiose, while xylanase activity increases the accessibility of cellulose to cellulases.

Softwood residues are the most abundant feedstock available for bioconversion in many northern countries. However, the high costs for delignification and enzymatic hydrolysis currently deter commercialization of softwood bioconversion processes. This study evaluates the abilities of two novel fungal preparations (MSUBC1 and MSUBC2) and two commercial cellulase preparations (TR1 and TR2) to hydrolyze cellulose in Douglas-fir pretreated by steam explosion or ethanol organosolv process. MSUBC1 showed significantly better performance than the other preparations on both lignocellulosic substrates. In particular, MSUBC1 achieved >76% cellulose conversion for hydrolysis of steam-exploded Douglas-fir (∼44% lignin) after 72 h at low enzyme loading (10 filter paper units/g of cellulose) and without β-glucosidase supplementation.

Twenty-nine cellulase preparations from different sources were compared interms of their abrasive activities (the ability to remove Indigo from denim) and their ability tosaccharify cellulose. Nodirectrelationship could be found between these two abilities. The preparations were divided into three groups: (1) with a high yield of reducing sugars after 24 h hydrolysis of Avicel cellulose but low abrasive activity; (2) universal cellulases that could both effectively hydrolyze cellulose and remove Indigo from denim; and (3) cellulase samples with high abrasive activity but low saccharification ability.

A model microassay system was developed to measure indigo back-staining on cotton fabrics in the presence of enzymes on a small laboratory scale. Backstaining indexes for 11 cellulase samples were measured, and the enzymes were ranked from lower to higher backstaining. Two multienzyme cellulase preparations were separated into fractions using chromatofocusing on a Mono P column. Adsorption ability and backstaining properties of purified enzyme fractions were studied. Evidence was obtained that protein adsorption on cotton fabrics is a crucial parameter causing backstaining (both for crude cellulase samples and purified enzyme components).