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At least 739 records · Page 41Linked to original sources
PubMed1980

[Purification and properties of low molecular weight endoglucanase of the cellulase complex from Trichoderma koningii].

A homogenous low molecular weight 1,4-beta-glucan glucanohydrolase (endoglucanase) has been isolated from a crude commercial preparation of cellokoningine P10X of T. koningii origin. The molecular weight of the enzyme as determined by polyacrylamide gel electrophoresis is 13 000. The endoglucanase was obtained as a lyophylized preparation free of the cellobiase activity. It was shown that cellobiose or methylcellobioside activate the effect of the low molecular weight endoglucanase (measured by the viscometric technique with respect to CMC hydrolysis) and at the same time almost completely suppress the activity of high molecular weight endoglucanases from the sane source. A detailed kinetic study of the effects showed that the low molecular weight enzyme is activated by a transglycosylation mechanism, where cellobiose acts as an added nucleophile. The activation is 6-fold at saturating concentrations of cellobiose (Ks = 15 mM). It was shown that diverse kinetic behaviour of cellobiose which can act both as activatory and inhibitor for endoglucanases from different sources can be explained, firstly, by different ratios of low to high molecular weight endoglucanases in the cellulase complexes, and, secondly, by their ability to catalyze transglycosylation reactions, which, in turn, results in a transfer of reducing end groups of the reaction products onto cellobiose as an added nucleophile.

Cellobiose↗
PubMedDate not supplied

[Detection of transglycosylation reactions under the influence of Trichoderma koningii and Trichoderma viride cellulase].

The transglycosylation reactions catalyzed by the low molecular weight endo-beta-1,4-glucanase from the cellulase complex of Trichoderma koningii as well as unseparated complexes from Tr. koningii and Tr. viride were investigated. The products obtained from the mixture of cellodextrine (donor, 0.5%) and p-nitrophenyl-beta-D-glucopyranoside (acceptor, 0.4%) with the aid of the above enzymes were analyzed. Transglycosylation products were separated by Sephadex G-15 gel-filtration. In all the three cases the highest molecular weight p-nitrophenyl glycosides of oligosaccharides (with a molecular weight of over 1500) were first synthesized and then hydrolyzed. At the beginning of the reaction the amount of p-nitrophenyl glycosides of oligosaccharides synthesized was greater than that of the reducing groups measured according to Nelson. Addition of p-nitrophenyl-beta-D-glucopyranoside to cellodextrine did not influence the rate with which the latter was hydrolyzed by endoglucanase.

Cellulase↗
PubMedDate not supplied

[Kinetics of xylanase and cellulase production by Ascobolus gamundii (Fungi, Ascomycotina)].

Growth and cellulase-xylanase enzyme systems production by Ascobolus gamundii were evaluated in synthetic media with or without natural inducers. The basal level of enzyme complexes was determined using glucose as carbon source. With crystalline cellulose, the amount of endoglucanase and beta-glucosidase was 2-4 times the basal, and the level of endoxylanase and beta-xylosidase was 3 times higher than that observed with glucose. When using xylan as carbon source, endoxylanase and endoglucanase were induced. The higher production of the enzyme systems was observed during the log-phase growth of A. gamundii with a mixture of cellulose and xylan as carbon source. The generalized induction of both enzyme complexes could be due to evolutive adaptation to the substrate (herbivore dung) in which cellulose and hemicellulose are associated to conform the plants cell-walls.

Ascomycota↗
PubMed1996

Differential scanning calorimetry of the irreversible thermal denaturation of cellulase from Streptomyces halstedii JM8.

High-sensitivity differential scanning calorimetry has been applied to characterize the irreversible thermal denaturation of a cellulase, assuming that thermal denaturation takes place according to the kinetic scheme N-k-->D, where k is a first-order kinetic constant that changes with temperature, as given by the Arrhenius equation; N the native state, and D the denatured one. On the basis of this model, the values of the rate constant as a function of temperature and the activation energy were calculated. The analytical data obtained with the fluorescence method as well by measurement of the enzymatic activity temperature dependence support this two-state kinetic model.

Calorimetry, Differential Scanning↗
PubMed1996

[Contribution to the study of the origin of cellulase activities of the gut in earthworm Eisenia fetida andrei].

In order to determine the origin of cellulases in the gut of the earthworm Eisenia fetida andrei, the wall tissues of the different parts of the disinfected gut are cultured in vitro. Enzymatic activities (FPase: filter paper activity; CMCase: carboxymethycellulase, cellobiase) were measured both in the tissues and in the culture medium: the following activities were found, carboxymethycellulase (CMCase), filter paper activity (FPase). The first located in the crop, gizzard and midgut wall, the second in the foregut and midgut wall. The cellobiase was detected only in the crop and gizzard tissues, whereas it is present in each part of the gut of holoxenic worms. This fact indicates that this enzyme is mainly produced by microorganisms ingested. These results allow us to propose the hypothesis of the existence of synergy, for the cellulose hydrolysis between tissular enzymes and cellulolytic microorganisms.

Amylases↗
PubMedDate not supplied

[Effect of culture conditions on the production of cellulases by Trametes trogii].

Production of the components of the cellulase complex by Trametes trogii was investigated under different culture conditions. Endoglucanase, exoglucanase and beta-glucosidase were produced by Trametes trogii under shaken and stationary conditions using crystalline cellulose as the only carbon source. No marked differences were found for endo- and exoglucanase production between both culture conditions. In shaken cultures beta-glucosidase values doubled those obtained in stationary conditions. All maxima were reached approximately 10 days earlier in static cultures than in shaken ones. The addition of glucose to the culture medium improved growth but decreased abruptly the enzyme production. The optimal pH of the medium for the synthesis of the enzymes was 5.6, and the best incubation temperature was 25-28 degrees C. Enzyme activities were maximal at pH 3.1 and 45 degrees C (endoglucanase), pH 4.1 and 50 degrees C (exoglucanase) and pH 5.3 and 60 degrees C (beta-glucosidase).

Basidiomycota↗
PubMed1985

In vivo cloning of the pectate lyase and cellulase genes of Erwinia chrysanthemi.

Using an RP4 plasmid which carries a mini-Mu prophage which allows it to integrate spontaneously random pieces of its host chromosome, we cloned in vivo at least some of the pectate lyase and cellulase genes of the Erwinia chrysanthemi strain B374. The RP4-prime plasmids were used to localize the cloned genes on the B374 chromosome by co-transposition mapping and to subclone most of the genes in a classic high copy number plasmid vector.

Journal Article↗
PubMed1994

Veratryl alcohol oxidase activity of a chemically modified cellulase protein.

A cellulase, cellobiohydrolase I (CBH I) from Trichoderma reesei was chemically modified by covalent attachment of pentaammine ruthenium (III) without loss in hydrolytic activity. Data suggest that such a modification endowed CBH I with oxidoreductase activity. The modified enzyme was able to carry out hydrogen peroxide-dependent oxidation of veratryl alcohol, a substrate for lignin peroxidase, at a rate of 0.148 mumol substrate oxidized min-1 mumol-1 enzyme. The effects of pH, temperature, and substrate concentration on the oxidation reaction were examined. The optimal temperature was determined to be 45 degrees C, and the optimal pH was 4.3. The Km and Vmax for veratryl alcohol were determined to be 3.519 mM and 52.27 microM min-1, respectively. Tartrate at concentrations as low as 0.10 mM was found to inhibit the reaction.

Alcohol Oxidoreductases↗
PubMed1995

Multiple roles of the cellulase CBHI in enhancing production of fusion antibodies by the filamentous fungus Trichoderma reesei.

The production of Fab antibody fragments in Trichoderma reesei can be increased over 50-fold by fusing the core-linker region of the T. reesei cellulase CBHI (cellobiohydrolase I) to the heavy Fd chain (Nyyssönen et al. 1993). This beneficial role of CBHI in antibody production has now been studied further by comparisons of T. reesei trains producing the light chain only. Fab or CBHI-Fab all of which exhibited identical light chain integration. The N-terminal fusion of CBHI to the heavy Fd chain not only aided secretion, as expected, but also increased the level of mRNA encoding the CBHI-heavy Fd chain, either by stabilizing the messenger or by enhancing transcription. The CBHI part appeared to facilitate secretion at least by aiding the passage through the endoplasmic reticulum, since processing of the signal peptide of the antibody chains seemed to be most efficient in the strain producing CBHI-Fab in contrast to the strains producing light chain or Fab fragment. Interestingly, CBHI core-linker protein, originating from the CBHI-heavy Fd chain, was found in large amounts in the culture medium. The cleavage resulting in this tailless CBHI occurred inside the cell. This suggests that, by omitting the heterologous tail, the secretion of the resulting CBHI core-linker protein is enhanced to a level comparable with secretion of the extracellular T. reesei proteins.

Cellulose 1,4-beta-Cellobiosidase↗
PubMed1991

Production of extracellular cellulase by Lunulospora curvula and Flagellospora penicillioides.

Studies on the production of extracellular cellulase in two aquatic hyphomycetes Lunulospora curvula and Flagellospora penicillioides have shown that several factors such as carbon source, nitrogen source, pH and temperature affect the production of the enzyme. Experiments have shown that carboxymethyl cellulose is the best source of carbon, and ammonium sulfate is the best source of nitrogen for the production of the enzyme. An optimum pH of 5.2 and a temperature of 28 degrees C was found to favor maximum enzyme activity in 12-d-old cultures. Glucose and sucrose were found to suppress the activity of the enzyme in both organisms.

Culture Media↗
PubMed1999

Preparation of High Yields of Algal Protoplasts Using Buccal Juice of Sea Hare and Commercial Cellulase.

; Buccal juice of the sea hare Aplysia juliana was found to degrade algal polysaccharides. The optimal enzyme composition for protoplast preparation from Undaria pinnatifida was protein at 48 µg/ml buccal juice from sea hare, 10 mg/ml cellulase Onozuka-RS, 0.4 M NaCl, 0.8 M sorbitol, 2 mg/ml dextran sulfate sodium salt, and 1 µl/ml 2-mercaptoethanol in 10 mM MES buffer (pH 6.0). Protoplasts of Eisenia bicyclis, Endarachne binghamiae (Phaeophyta), and Ulva pertusa (Chlorophyta) could also be prepared in a similar manner. Yields of these protoplasts were about 10(7) cells per gram of fresh weight alga.

Journal Article↗
PubMed1996

Cloning and Characterization of Two Closely Linked Cellulase Genes from Cellvibrio mixtus

A 16.5-kb BamHI fragment of the Cellvibrio mixtus chromosome was found to direct carboxymethylcellulase, xylanase, and avicel hydrolysis. Two closely linked genes were subcloned from this insert. The gene, cmcI, was cloned as a 2.7-kb fragment and expressed in Escherichia coli. It encoded an enzyme of approximately 74 kDa which degraded carboxymethylcellulose and xylan but did not attack the microcrystalline cellulose substrate avicel. A second cellulase capable of degrading avicel, encoded by exoI, was found 5.5 kb downstream of cmcI. Two translation products of 53.7 kDa and 51.5 kDa were produced in E. coli strains expressing exoI. Northern analysis of total mRNA of C. mixtus grown on avicel, with a probe generated from cmcI, showed that cmcI and exoI were not cotranscribed in an operon.

Journal Article↗
PubMed1991

Genetic engineering of Trichoderma to produce strains with novel cellulase profiles.

Genetic engineering has been used to modify the proportion of different cellulases produced by a hypercellulolytic Trichoderma reesei mutant strain. A general expression vector, pAMH110, containing the promoter and terminator sequences of the strongly expressed main cellobiohydrolase 1 (cbh1) gene was used to overexpress a cDNA coding for EGI, the major endoglucanase (1,4,beta-D-glucan glucanohydrolase, EC 3.2.1.4). An in vitro modified cbh1 cDNA, incapable of coding for active enzyme, was used to inactivate the major cellobiohydrolase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) gene. In this way, new strains producing elevated amounts of the specific endoglucanase 1 (EGI) and/or lacking the major cellobiohydrolase (CBHI) were produced, and these have been further characterized.

Base Sequence↗
PubMed1987

Seasonal variation in amylase, invertase, cellulase activity and carbon dioxide evolution in a tropical protected grassland of Orissa, India, sprayed with carbaryl insecticide.

A distinct seasonal variation in the enzyme activities and carbon dioxide evolution in soil, with a maximum in summer, was observed in soil treated with carbaryl and in control soil. There was no significant difference in the rate of enzyme activity between 0 and 10 cm and 10 and 20 cm depth of soil. Carbaryl insecticide applied at a normal agricultural dose did not have any inhibitory effect on soil enzyme activity, or on the rate of CO(2) evolution. However, the cellulase activity was greater in the surface soil of the control plot than in the treated plot.

Journal Article↗
PubMed2000

The influence of culture conditions on mycelial structure and cellulase production by Trichoderma reesei Rut C-30.

The morphology of Trichoderma reesei Rut C-30, during submerged cultivations in shake flask, was examined. The influence of the size inoculum and the composition of the fermentation medium on the morphology and cellulase production was studied. Different inoculum sizes were studied but the significative change in fungus morphology was observed for spores concentration between 10(5) and 10(7) spores/ml (i.e. 10(2) and 10(4) spores/ml in pre-culture medium). In the medium without Tween 80, at low inoculum size, the majority of the pellets were large and well individualized, in contrast, at higher inoculation densities small flocs were obtained, with higher production of soluble protein and higher filter paper activity. It was found that the average pellet size seems to be inversely proportional to the inoculum size. Medium composition, namely Tween 80, also influences the morphology of T. reesei Rut C-30 and enzyme production. The presence of Tween 80 in fermentation medium inhibited the pellet formation of this strain.

Journal Article↗
PubMed2000

On-line parameter estimation of industrial fermentation process with an alkaliphilic cellulase-producing bacterium by exhaust gas analysis.

A method for on-line estimation of the fermentation parameters (substrate, product, and cells) of an alkaliphilic Bacillus sp. by utilizing data on the O2 and CO2 tensions in the exhaust gas and the pH of the fermentation broth was investigated. The estimation was based on the stoichiometric relations concerning the weight of CO2 formed, O2 consumed, product formed, and substrate consumed by the bacterium and on the ratio of the mass of the product to that of the cell biomass. During the fermentation, in which the pH range was 7.8-8.8, the parameters were successfully estimated by considering the reactions of CO2 to produce HCO3- and/or CO3(2-) in the liquid-phase as well as the desorption of CO2 to the aeration gas. It was verified that the proposed estimation method is applicable to industrial-scale fermentation using an alkaliphilic cellulase-producing Bacillus sp. The correlation coefficients between the estimated and observed fermentation parameters exceeded 0.990, indicating that the method is capable of evaluating fermentation parameters with an accuracy satisfactory for industrial use.

Journal Article↗
PubMed2003

Optimization of aeration and agitation rates to improve cellulase-free xylanase production by thermotolerant Streptomyces sp. Ab106 and repeated fed-batch cultivation using agricultural waste.

Thermostable cellulase-free xylanase was produced by Streptomyces sp. Ab106 using agricultural waste, sugar cane bagasse, as the substrate at 50 degrees C and pH 7.0. The central composite face-centered experimental design was applied to evaluate the optimal agitation and aeration rates in a 5-l fermentor. The highest activity (16.0+/-0.5 IU/ml) was obtained at an aeration rate of 1 vvm and an agitation rate of 150 rpm (k(L)a = 351 h(-1)). Using the repeated fed-batch cultivation technique, the maximum xylanase activity of 32+/-1 IU/ml was obtained during the second cycle of repeated fed-batch culture.

Journal Article↗
PubMed1999

Isolation and transcriptional analysis of a cellulase gene (cell) from the basidiomycete Irpex lacteus.

A gene (named cell) homologous to the cellobiohydrolase I gene (cbhl) of Trichoderma reesei was isolated and sequenced from the white rot basidiomycete Irpex lacteus MC-2. The cell open reading frame consists of 1551 bp, which is interrupted by two introns, encoding a polypeptide of 517 amino acid residues with a calculated molecular mass of 54,522 Da. The deduced amino acid sequence showed that CEL1 (the protein encoded by cell) has a modular structure consisting of a catalytic domain of 449 amino acids and a C-terminal cellulose-binding domain (CBD) of 36 amino acids separated by a proline-, serine-, threonine-rich linker region of 32 amino acids. The CEL1 catalytic domain is homologous with fungal cellobiohydrolases (CBHs) belonging to family 7 of the glycosyl hydrolases. The transcription of cell was induced in the presence of various cellulosic substrates and repressed by glucose. It was therefore concluded that the reported sequence represents the first cellulase gene isolated from the basidiomycete Irpex.

Journal Article↗