Cellulase isolation

Two cellulases isolated from culture filtrates of Trichoderma viride caused only a slight decrease in the DP of native cellulose, but a rapid decrease in that of reprecipitated cellulose. Both enzymes have the ability to release free fibres from filter paper. 

Isolation of mutations increasing pectinase synthesis led to the characterisation of the pecS locus (67). Inactivation of pecS results in derepressed synthesis of pectinases, of the cellulase CelZ, of the secretion machinery and of an extracellular insoluble blue pigment (Figure 4). 

The cambium was isolated firom spruce (Picea abies) logs felled in October-November. The bark was stripped off, and the cambium was removed by gentle scraping. The isolated cambium was immediately fiozen in liquid nitrogen and fi-eeze-dried. The carbohydrate composition of the isolated cambium was analysed by HPLC after enzymatic hydrolysis using Pectinex Ultra and a mixture of cellulases and hemicellulases (Buchert et al 1993). 

Three laccase preparations (I, II and III) were isolated from the racellular culture medium of Coriolus versicolor by consecutive fractionation through Sephadex G50 and DEAE Sephadex A25 (84). The laccase III preparation at pH 4.0 reduced the apparent molecular weight of a lignin-derived fraction that had been obtained by eluting the water-soluble extract of a cellulase treated ezomatsu wood residue through... 

Because of the availability of this remarkably extensive physical picture of the CBH I molecule (as well as the potential availability in adequate quantities of the purified enzyme itself), DSC studies can provide vduable insights into structure-function relationships for this important cellulase. We present here a comparison of DSC analyses of the intact CBH I molecule with those of the isolated catalytic-domain and tail-region proteolytic fragments. 

RunUnococcus albus and Ruminococcus flavefadens. These bacteria are important cellulose-degraders found in the rumen of cattle and sheep (2). Most isolated strains ferment cellulose and xylan and all ferment cellobiose. Fermentation of glucose and some other carbohydrates depends on the particular strain. R flavefadens and B. succinogenes can ferment the highly ordered crystalline cellulosic su trates but R albus cannot. No evidence has been found for extracellular cellulase production by R albus, but Ohmiya et al. purified cellobiosidase from this culture 17). Laboratory growth of R albus has been conducted at pH 7.0 and 37 C. 

Much effort has been expended over the years on increasing enzyme production of T. reesei by isolation of high yielding mutants and optimizing media and fermentation conditions. Strains have been isolated that produce 2-6 times the cellulase productivity of the parent wild strain (QM 6a) in batch culture. The mutants produce higher levels of cellulase protein but the specie activity of the enzymes and the proportions of the individual components (ca. 30% endo- -glucanase, 70% o- -glucanase, and less 1% cellobiase) are similar to those of the parent. 

Similar results were obtained with crude cellulase preparations from Penicillium pinophilum (12). The general applicability of this biospecific chromatography is illustrated by the isolation of the EGD from C. t., cloned in E. c. (Fig. 6). 

T. harzianum IMI 275950 isolated from wheat straw grew better on lignocellulose (Table I). Despite these differences, the enzyme yields of the cellulase/xylanase complexes did not correlate with growth rate. These observations from this empirical study indicate that strains isolated or derived for growth on extracted substances may not necessarily be the most useful strains to exploit natural substrates. 

In the reported structures of products of cellulase digestion of xyloglucans from different sources, there has been considerable variation that may reflect different action-patterns of enzyme preparations as much as actual differences in the structures of the polysaccharides. On reaction of xyloglucan from the walls and culture medium of suspension-cultured, sycamore cells,26,27 four major oligosaccharide products were isolated. Stuctures were proposed for the heptamer (Z) and the nonamer (3). 

Hydrolysis with cellulase released 0-D-Man-(l - 4)-d-G1c, 36, and the pentasaccharide having the proposed structure 36b, as well as the hexasac-charide with an additional galactosyl group /3-d-( 1 - 2)-linked to the (1 6)-a-D-galactosyl unit. The isolation of these products having a substituent... 

Enzyme (3-glucosidase, almond-isolate or cellulase, Aspergillus niger extract... 

This study describes an absolute method for the evaluation of endo-/ -glucanase (Cx) or endocellulase activities in the cellulase complex without the need of a time-consuming isolation of the endocellulase fractions. In the method proposed by Almin et al. (3), an assumption was needed in the theoretical derivation of endocellulase activities, namely, that Mv/Mn is constant in the initial stages of the enzymic reactions. We found, however, a linear relationship between Mv and STn. They used CMC as substrate, and since the mode of action of endocellu-lases on CMC can be regarded as similar to that on HEC, it is possible that their assumption is not fulfilled. 

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