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At least 397 records · Page 22Linked to original sources
PubMed1979

Secretion of cellulase and beta-glucosidase by Trichoderma viride ITCC-1433 in submerged culture on different substrates.

Trichoderma viride ITCC-1433 produces high yields of cellulase and especially beta-glucosidase when grown in submerged culture on different carbon sources. Cellulase synthesis was strongly repressed in the presence of glucose and only a low constitutive activity of beta-glucosidase and carboxymethylcellulase, but no Avicelase, could be demonstrated when culturing T. viride on glucose. With carboxymethylcellulose (CMC) as a substrate the secretion of enzyme as well as growth depended on the degree of substitution, but in general CMC cannot be regarded either as a powerful inducer or as a carbon source. With insoluble cellulose, maximum enzyme production and activities were obtained using an alkali-treated cellulose powder. On this substrate the excretion of soluble protein into the culture broth increased and the protein concentration corresponded to cellulolytic activities.

Cellulase↗
PubMed1980

Stability of the cellulase of Trichoderma reesei under use conditions.

Enzyme stability studies have been reinvestigated under the conditions used for cellulose hydrolysis (pH 4.8, 50 degrees C, 24 hr). The cellobiohydrolase (CBH) component as measured on Avicel is less stable than other enzymes of the cellulase complex, and is 60% inactivated by merthiolate (and other Hg compounds) under the above conditions. Endo-beta-1,4-glucanase is much more stable, and more resistant to merthiolate and other compounds. Under unshaken conditions the Avicelase of the Rutgers strain C 30 shows greater stability to heat than that of other available strains. Biocides must be selected not only for their ability to prevent contamination, but also for their compatibility with cellulases. Tetracycline and chlortetracycline are inexpensive, effective in very low concentrations, have no harmful effect on the enzymes, and are compatible with the yeasts that subsequently grow on the sugar solutions to produce alcohol. Attempts have been made to stabilize the enzymes by chemical modification in such a way as to maintain their solubility. Glutaraldehyde treatment greatly increased the enzyme size, lowered the pI values, and gave a slight shift in the pH activity curve. There was, unfortunately, no increase in enzyme stability, and the activity of enzymes on solid celluloses was adversely affected. Shaking greatly reduced the hydrolysis of Avicel by Trichoderma reesei C 30 enzyme. The adverse effect was accompanied by a decrease in recoverable enzyme and protein.

Anti-Infective Agents, Local↗
PubMed1977

The medical dissolution of phytobezoars using cellulase.

Phytobezoars are plant fibre concretions occurring in the stomach as a complication following some types of gastric surgery. Symptoms include distension, pain and vomiting. Ulceration, gastric bleeding and even perforation can occur. If untreated, they result in a significant mortality. Dissolution of the phytobezoar can be achieved without operative intervention. Enzymes and especially cellulase help to break up the mass and it can then be aspirated or allowed to pass on. Five patients with phytobezoars were thus treated and the cellulase method was confirmed to be simple, safe and effective.

Adult↗
PubMed1996

Isozyme polymorphism of cellulases in Aspergillus terreus.

Maximum cellulase production in Aspergillus terreus was obtained at a temperature of 28 degrees C, pH 4.0 and a substrate concentration of 1% CMC. Variability in cellulase enzyme production and isozyme polymorphism of endo-beta-1,4-glucanase and beta-1,4-glucosidase was studied in 45 natural isolates of A. terreus. Different electrophoretic patterns were evident for endoglucanase. Three zones of activity viz EG 1, EG 11 and EG 111 were observed showing different electrophoretic mobilities. Some of the isolates exhibited the presence of null alleles for EG 1. During development EG 1 and EG 11 were observed throughout while EG 111 appeared on the eighth day. For beta-1,4-glucosidase two zones of activity viz beta-glu 1 and beta-glu 11 were observed. beta-glu 1 showed variable electrophoretic mobilities. beta-glu 1 appeared throughout during development while beta-glu 11 appeared on the twelfth day.

Alleles↗
PubMed1995

The cellulase system of the anaerobic rumen fungus Neocallimastix frontalis: studies on the properties of fractions rich in endo-(1-->4)-beta-D-glucanase activity.

Seven fractions rich in endoglucanase activity were separated from the extracellular cellulase system of the anaerobic rumen fungus Neocallimastix frontalis. The fractions (ES1, ES3, ES2U1, ES2U2, ES2U4, ES2U3C1 and ES2U3C2) were separated from each other and from a fraction that could solubilize crystalline cellulose (the so-called crystalline-cellulose-solubilizing component, CCSC) by the sequential use of differential adsorption on the microcrystalline cellulose Avicel, gel filtration and affinity chromatography on concanavalin-A-Sepharose. The molecular masses of the endoglucanase fractions, when determined by gel filtration, were 64, 30, 61, 113, 17, 38 and 93 kDa respectively. Each enzyme degraded carboxymethylcellulose and was rich in activity to cellulose swollen in phosphoric acid to break the hydrogen bonding: cellobiose, cellotriose and cellotetraose were released in differing proportions. Each fraction showed a characteristic gradient when the capacity of each enzyme to increase the fluidity of a solution of carboxymethylcellulose was plotted against the increase in reducing power of the solution. Although neither endoglucanase fraction, acting in isolation, could degrade crystalline cellulose, three of the fractions (ES1, ES3 and ES2U1) could act synergistically with the CCSC fraction in this regard. Remarkably, the same three fractions also acted in synergism with the cellobiohydrolases (CBH I and CBH II) of the aerobic fungus Penicillium pinophilum in degrading crystalline cellulose, but only when both cellobiohydrolase enzymes were present in the solution along with any one of the three endoglucanases. These observations support the conclusion that the mechanism of action of the cellulase system of N. frontalis in degrading crystalline cellulose may be similar to that operating in the aerobic fungi.

Anaerobiosis↗
PubMed1990

Sequence analysis of the Clostridium stercorarium celZ gene encoding a thermoactive cellulase (Avicelase I): identification of catalytic and cellulose-binding domains.

The nucleotide sequence of the celZ gene coding for a thermostable endo-beta-1,4-glucanase (Avicelase I) of Clostridium stercorarium was determined. The structural gene consists of an open reading frame of 2958 bp which encodes a preprotein of 986 amino acids with an Mr of 109,000. The signal peptide cleavage site was identified by comparison with the N-terminal amino acid sequence of Avicelase I purified from C. stercorarium culture supernatants. The recombinant protein expressed in Escherichia coli is proteolytically cleaved into catalytic and cellulose-binding fragments of about 50 kDa each. Sequence comparison revealed that the N-terminal half of Avicelase I is closely related to avocado (Persea americana) cellulase. Homology is also observed with Clostridium thermocellum endoglucanase D and Pseudomonas fluorescens cellulase. The cellulose-binding region was located in the C-terminal half of Avicelase I. It consists of a reiterated domain of 88 amino acids flanked by a repeated sequence about 140 amino acids in length. The C-terminal flanking sequence is highly homologous to the non-catalytic domain of Bacillus subtilis endoglucanase and Caldocellum saccharolyticum endoglucanase B. It is proposed that the enhanced cellulolytic activity of Avicelase I is due to the presence of multiple cellulose-binding sites.

Amino Acid Sequence↗
PubMed1990

Cloning and sequence analysis of a cDNA for cellulase (FI-CMCase) from Aspergillus aculeatus.

We have cloned and characterized the cDNA coding for a major component of cellulase, endoglucanase (FI-CMCase), produced by Aspergillus aculeatus. The cDNA was isolated from a A. aculeatus cDNA library using synthetic oligonucleotide mixtures that correspond to the internal amino acid sequence of the mature FI-CMCase protein. Nucleotide sequence analysis of the cloned cDNA insert revealed a 711 bp open reading frame that encoded a protein of 237 amino acid residues. The primary structure of FI-CMCase deduced from the nucleotide sequence of cDNA agreed with that found by amino acid sequencing of peptide fragments obtained by digestion with several proteinases and cyanogen bromide cleavage. There may be a signal peptide sequence of 16 amino acid residues at the N-terminus. The molecular mass of the mature protein calculated from the cDNA is 24002 daltons, which compares favorably with molecular mass estimates of purified FI-CMCase obtained from SDS-PAGE (25000 Da). No distinct homology was found between the amino acid sequence of FI-CMCase and known cellulase sequences of other microorganisms. This study is the first example of cDNA cloning of an endoglucanase from the genus Aspergillus.

Amino Acid Sequence↗
PubMed1977

[The cellulase enzyme system during growth and development of Acanthamoeba castellanii (author's transl)].

It could be shown that extracts of growing cultures of Acanthamoeba castellanii contained a cellulose degrading system. Reducing sugars are split off by one component of this system at an optimum of pH 4, another enzyme changes the viscosity at an optimum of pH 6, and a third component is a beta-glucosidase with an optimum at pH 3.5. At pH 4 the cellulose degradation products are cellobiose and glucose; at pH 6 higher molecular weight oligosaccharides are produced. During the development from trophozoites to cysts in a nutrient-free medium, the activities of both cellulases decline: Prior to the start of cellulose synthesis only 30%, and in cysts only 10% of the original existing activities are detectable. The biological function of the cellulase enzyme system is discussed together with a consideration of the fact that excystment takes place without digestion of the cyst wall in which the cellulose is deposited.

Amoeba↗
PubMed1982

A convenient procedure for the estimation of cellulase activity.

The extent of clarification of cellulose-containing agar by "complete' cellulase is a linear function of the logarithm of the enzyme activity. This fact allows a convenient and quantitative estimation of cellulase activity in culture filtrates to be made without the need for tedious dilution. Moreover, such activity can be determined even in the presence of inhibitors such as cellobiose.

Ascomycota↗
PubMed1993

Structural features of the Clostridium thermocellum cellulase SS gene.

The Clostridium thermocellum cellulase SS is a subunit of the extracellular cellulase complex (cellulosome). It has previously been shown that SS, hydrolyzes crystalline cellulose synergistically with another subunit, SL. To study this synergism further, the authors cloned the gene coding for SS (celS) and compared its sequence to other known cel genes. The celS, although unique in its DNA sequence, has many structural features similar to those found in other cel genes. These features include a ribosome biding site, signal peptide sequence, the existence of a conserved reiterated amino acid sequence, and a palindromic structure downstream from its open reading frame.

Amino Acid Sequence↗
PubMed1992

Synergism between Clostridium thermocellum cellulases cloned in Escherichia coli.

We have obtained a synergistic effect during degradation of Avicel and filter paper by Clostridium thermocellum cellulases (two endoglucanases and one cellobiohydrolase) cloned in Escherichia coli. The highest degree of synergism was found at early stages of reaction, during the first 20 h: 2.5 and 2.9 on Avicel and filter paper, respectively. During combined action of all three cellulases the main product is cellobiose.

Cellobiose↗
PubMed1996

Production, characterization and application of the cellulase-free xylanase from Aspergillus niger.

The effects of carbon source on xylanase and cellulase production were studied. The extract of steam-exploded corn stover was found to be the best raw material for producing cellulase-free xylanase. The xylanolytic enzymes of Aspergillus niger An-76 were purified by chromatography, and the properties of the four purified components were analyzed. When the enzyme was used to treat the birch Kraft pulp, and followed by a subsequent CEH bleaching, a brightness of 6.8% SBD more than that of the untreated one using the same chlorine dosage, or a saving of nearly 50% of chlorine consumption with the same brightness, was realized.

Aspergillus niger↗
PubMed1997

The bifunctional enzyme chitosanase-cellulase produced by the gram-negative microorganism Myxobacter sp. AL-1 is highly similar to Bacillus subtilis endoglucanases.

The gram-negative bacterium Myxobacter sp. AL-1 produces chitosanase-cellulase activity that is maximally excreted during the stationary phase of growth. Carboxymethylcellulase zymogram analysis revealed that the enzymatic activity was correlated with two bands of 32 and 35 kDa. Ion-exchange-chromatography-enriched preparations of the 32-kDa enzyme were capable of degrading the cellulose fluorescent derivatives 4-methylumbelliferyl-beta-D-cellobioside and 4-methylumbelliferyl-beta-D-cellotrioside. These enzymatic preparations also showed a greater capacity at 70 degrees C than at 42 degrees C to degrade chitosan oligomers of a minimum size of six units. Conversely, the beta-1,4 glucanolytic activity was more efficient at attacking carboxymethylcellulose and methylumbelliferyl-cellotrioside at 42 degrees C than at 70 degrees C. The 32-kDa enzyme was purified more than 800-fold to apparent homogeneity by a combination of ion-exchange and molecular-exclusion chromatography. Amino-terminal sequencing indicated that mature chitosanase-cellulase shares more than 70% identity with endocellulases produced by strains DLG, PAP115, and 168 of the gram-positive microorganism Bacillus subtilis.

Amino Acid Sequence↗
PubMed2002

Clostridium thermocellum cellulase CelT, a family 9 endoglucanase without an Ig-like domain or family 3c carbohydrate-binding module.

The celT gene of Clostridium thermocellum strain F1 was found downstream of the mannanase gene man26B [Kurokawa J et al. (2001) Biosci Biotechnol Biochem 65:548-554] in pKS305. The open reading frame of celT consists of 1,833 nucleotides encoding a protein of 611 amino acids with a predicted molecular weight of 68,510. The mature form of CelT consists of a family 9 cellulase domain and a dockerin domain responsible for cellulosome assembly, but lacks a family 3c carbohydrate-binding module (CBM) and an immunoglobulin (Ig)-like domain, which are often found with family 9 catalytic domains. CelT devoid of the dockerin domain (CelTDeltadoc) was constructed and purified from a recombinant Escherichia coli, and its enzyme properties were examined. CelTDeltadoc showed strong activity toward carboxymethylcellulose (CMC) and barley beta-glucan, and low activity toward xylan. The V(max) and K(m) values were 137 micro mol min(-1) mg(-1) and 16.7 mg/ml, respectively, for CMC. Immunological analysis indicated that CelT is a catalytic component of the C. thermocellum F1 cellulosome. This is the first report describing the characterization of a family 9 cellulase without an Ig-like domain or family 3c CBM.

Amino Acid Sequence↗
PubMed2003

Efficient cellulase production by Trichoderma reesei in continuous cultivation on lactose medium with a computer-controlled feeding strategy.

A low-foaming hydrophobin II deletant of the Trichoderma reesei strain Rut-C30 was used for production of cellulases by continuous cultivation on lactose medium in a laboratory fermenter. The control paradigm of the addition of new medium to the continuous process was based on the growth dynamics of the fungus. A decrease in the rate of base addition to the cultivation for pH-minimum control was used as an indicator of imminent exhaustion of carbon source for growth and enzyme induction. When the amount of base added per 5 min computation cycle decreased below a given value, new medium was added to the fermenter. When base addition for pH control thereafter increased above the criterion value, due to increased growth, the medium feed was discontinued or decreased. The medium feeding protocol employed was successful in locking the fungus in the stage of imminent, but not actual, exhaustion of carbon source. According to the results of a batch cultivation of the same strain on the same medium, this is the phase of maximal enzyme productivity. The medium addition protocol used in this work resulted in a very stable continuous process, in which cellulase productivity was maintained for several hundred hours at the maximum level observed in a batch cultivation for only about 10 h. Despite a major technical disturbance after about 420 h, the process was restored to stability. When the cultivation was terminated after 650 h, the level of enzyme production was still maximal, with no signs of instability of the process.

Bioreactors↗
PubMed1996

Correlation of exons with functional domains and folding regions in a cellulase from Agaricus bisporus.

The cellulase gene cel3 has been isolated from Agaricus bisporus and sequenced. The 5'-end of the cel3 transcript was determined by primer extension and S1 nuclease protection. Putative regulatory elements have been identified in the cel3 promoter and 3'-untranslated regions. The cel3 coding region is interrupted by six short introns, two of which separate the coding regions for the three modules in the CEL3 protein: cellulose-binding domain, linker region, and catalytic domain. Three of the remaining four introns are positioned in regions coding for loops between structural moieties. Intron positions are conserved between cel3 and other related cellulases.

Agaricus↗
PubMed2005

Characterization and gene cloning of a cold-active cellulase from a deep-sea psychrotrophic bacterium Pseudoalteromonas sp. DY3.

The celX gene encoding an extracellular cold-active cellulase was isolated from a psychrotrophic bacterium, which was isolated from deep-sea sediment and identified as a Pseudoalteromonas species. It encoded a protein consisting of 492 amino acids with a calculated molecular mass of 52.7 kDa. The CelX consisted of an N-terminal catalytic domain belonging to glycoside hydrolase family 5 and a C-terminal cellulose-binding domain belonging to carbohydrate-binding module family 5. The long linker sequence connecting both domains was composed of 105 residues. The optimal temperature for cellulase activity of CelX was 40 degrees C. The enzyme was most active at pH 6-7 and showed better resistance to alkaline condition. The zymogram activity analysis indicated that the CelX consisted of single enzyme component. The cellobiose was main hydrolysate of CelX.

Amino Acid Sequence↗
PubMed1998

Cellulosome and noncellulosomal cellulases of Clostridium cellulovorans.

This paper reviews the properties of the cellulosome and noncellulosome cellulases produced by Clostridium cellulovorans, an anaerobic, mesophilic, spore-forming microorganism that produces copious amounts of cellulase. The three major subunits of the cellulosome, CbpA, exoglucanase S (ExgS), and P100, are described, as well as the properties of the functional domains of CbpA. The properties of two noncellulosomal endoglucanases, EngD and EngF, are compared. The functions of the cellulose-binding domain (CBD) of CbpA indicate its potential uses in biotechnology.

Amino Acid Sequence↗