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PubMed2000

Effect of culture conditions of Pleurotus ostreatus (Fr.) Kumm. on cellulases complexes activity in post-cultivated substrates.

The aim of the presented research was to settle conditions and parameters of Pleurotus ostreatus (Fr.) Kumm. culture and to determine activity and yield of cellulase complexes biosynthesised by this mushroom on different substrates. Wheat straw sterilized by evaporation at temperature 58-60 degrees C during 48 hours was the first substrate. Wheat straw with Reynoutria japonica (Houtt) in 1:1 proportion, sterilized by irradiation (15 kGy), was the second, two-component, substrate. According to the obtained results it can be ascertained that P. ostreatus (Fr.) Kumm. grows and yields well on all kinds of substrates biosynthesising active cellulase complexes E.C. 3.2.1.4. glucohydrolases, both endo- and exogluconase, and E.C. 3.2.1.21. beta-glucosidase.

Cellulase↗
PubMed1991

Characterization and structure of the cellulase gene of Bacillus subtilis BSE616.

The Bacillus subtilis carboxymethyl cellulase (CMCase) gene originally cloned on a 3.2-kb PstI DNA fragment has been localized in a 1.5-kb Sau3AI fragment by a series of subclonings into plasmid pUC19. During the process the promoter region and Shine-Dalgarno (SD) sequence were deleted, but the 1.5-kb insert was shown to direct the synthesis of CMCase in scherichia coli to a high level, probably with the aid of lac promoter. We analyzed the complete nucleotide sequence of the CMCase gene. The CMCase gene is 1500-bp long, encoding a polypeptide of 499 amino acids and a stop codon. The putative "-35" region (TAGACA), "-10" region (TACAAT), and ribosome binding site (RBS) (AAGGAGG) have also been identified in the 5' flanking region. Comparison of the nucleotide sequence to three other published endo-beta-1,4-glucanase genes of B. subtilis strains shows that these sequences share very strong homology. It seems that the cellulase genes have been derived from a common ancestor by spontaneous mutation. The probability of carboxy-terminal processing of the CMCase protein is also discussed.

Amino Acid Sequence↗
PubMed1992

Mixed cultivation of Trichoderma reesei and Aspergillus ochraceus for improved cellulase production.

Aspergillus ochraceus IMI 317911 was screened to be a high cellobiase producing strain (2.40 IU/ml). The mixed batch cultivation of Trichoderma reesei QM 9414/Rut C-30 and A. ochraceus IMI 317911 resulted in a balanced enzyme as compared to singly grown cultures. The milled rice straw (6%, w/v) as carbon source was found suitable for production of cellulases resulting in a Filter Paper Activity (FPA) of 1.83 IU/ml and a cellobiase production of 1.63 IU/ml after 7 days of stirred cultivation. An overall cellulase productivity of 10.89 IU/l/h and an enzyme ratio to cellobiase of 1.12 was achieved.

Aspergillus ochraceus↗
PubMed2006

[Cloning and identification of cellulase genes from uncultured microorganisms in pulp sediments from paper mill effluent].

The metagenomic DNA of pulp sediments from paper mill effluent was extracted and purified. The 16S rDNA was amplified using the purified metagenomic DNA as template and a 16S rDNA library was prepared. Sequence analysis of 16S rDNA clones showed that diverse of uncultured bacteria inhabit in this environment, which can be classified into 4 clusters as Spirochaetes, Proteobacteria, Bacteroidetes and Firmicutes. A metagenomic library containing 10000 clones was constructed into cosmid vector, and the capacity of inserted DNA of which was 3.53 x 10(8) bp. Functional screening of the library resulted in isolation of two independent clones expressing endoglucanase activity, three independent clones expressing exoglucanase activity and two independent clones expressing beta-glucosidase activity. One clone expressing strongest enzyme activity from each activity category was chosen to be further analyzed. Three novel cellulase genes designated as umcel5L, umcel5M and umbgl3D were identified by subcloning, sequencing and expression. The umcel5L encodes an endoglucanase belonging to glycosyl hydrolase family 5, which is most related to an endoglucanase from Bradyrhizobium japonicum at 43% identity and 59% similarity. The umcel5M encodes a cellodextrinase belonging to glycosyl hydrolase family 5, which is most similar to a cellodextrinase from Fibrobacter succinogenes at 48% identity and 69% similarity. The umbgl3D encodes a putative beta-glucosidase belonging to glycosyl hydrolase family 3, which shares highest homology with a beta-glucosidase from Thermotoga maritima at 46% identity and 61% similarity. It is the first time to reveal the bacterial diversity of pulp sediments from paper mill effluent and clone novel cellulase genes from the bacteria by culture-independent method.

Bacteria↗
PubMed1975

Purification and characterization of two cellulases from auxin-treated pea epicotyls.

Two forms of beta-1,4-glucan 4-glucanohydrolase (EC 3.2.1.4) were extracted from growing regions of Pisum sativum epicotyls which had been treated with the auxin, (2,4-dichlorophenoxy)acetic acid. One cellulase is buffer-soluble, the other buffer-insoluble but extractable with high salt concentrations. Both enzymes catalyze endohydrolysis of carboxymethylcellulose with the same pH optimum (5.5 to 6.0). They were purified with the use of DEAE-cellulose chromatography, Sephadex gel filtration, and ultrafiltration. They are distinct proteins as characterized by: electrofocusing and disc gel electrophoresis (pI values = 5.2 and 6.9, respectively); mobility in sodium dodecyl sulfate polyacrylamide gels, fractionation on Sephadex, and sedimentation in the ultracentrifuge (mol wt = approximately 20,000 and 70,000, S values 2.63 and 3.73); and immunological properties. The buffer-soluble enzyme tends to dimerize on purification. Amino acid analyses show that the buffer-soluble enzyme is relatively rich in glycine, alanine, and valine and deficient in cystine, tryosine, and phenylalanine compared to the buffer-insoluble enzyme. The two cellulase activities were generated in approximately equal amounts after auxin treatment. Within 5 days their levels had increased at least 100-fold and they constituted about 0.1% of total cellular protein. Present data indicate that one is not derived from the other.

Amino Acids↗
PubMedDate not supplied

[Effect of fungal cellulases on enzymic activity of malt].

In order to increase malt enzymic activity, cellulases from the fungus Geotrichum candidum were used. Malt milk was processed for 1--3 hr at 40 degrees C and pH 6.0--6.5 by the fungal preparation or culture fluid filtrate used in such quantities in which there were 0.5 to 9.0 units of cellulase activity per g malt. During the process enzymic activities of malt increased significantly: dextrinating activity--by 73%, amylolytic activity--by 60--100%, saccharifying activity--by 3.4 times, and proteolytic activity--by 2 times.

Cellulase↗
PubMed1984

Mode of action and substrate specificities of cellulases from cloned bacterial genes.

Three recombinant plasmids, pEC1, pEC2, and pEC3, each containing a unique Cellulomonas fimi chromosomal DNA insert, expressed Cm-cellulase activities in Escherichia coli C600 (Whittle, D. J., Kilburn, D. H., Warren, R. A. J., and Miller, R. C., Jr. (1982) Gene (Amst.) 17, 139-145; Gilkes, N. R., Kilburn, D. G., Langsford, M. L., Miller, R. C., Jr., Wakarchuk, W. W., Warren, R. A. J., Whittle, D. J., and Wong, W. K. R. (1984) J. Gen. Microbiol. 130, 1377-1384). Viscometric and chemical analyses showed that the enzymes encoded by pEC2 and pEC3 behaved as endoglucanases, whereas that encoded by pEC1 behaved as an exoglucanase. The activities of the exoglucanase and the pEC2-encoded endodglucanase were additive on Cm-cellulose as substrate. The pEC1-encoded enzyme also hydrolyzed xylan and p-nitrophenyl cellobioside. Two substrate-bound Cm-cellulases were isolated from the residual cellulose in a C. fimi culture by guanidine hydrochloride elution, affinity chromatography, and polyacrylamide gel electrophoresis. Both were glycoproteins of apparent Mr = 58,000 and 56,000, respectively. The 56-kDa enzyme appeared to be identical with the pEC1-encoded product, suggesting that they arise from the same gene.

Actinomycetales↗
PubMedDate not supplied

[Fractionation of the cellulase complex of the fungus Aspergillus terreus].

A procedure for isolating a complex of extracellular cellulases from the Aspergillus terreus culture liquid using SP-Sephadex C-50 has been developed. Enzymatically and electrophoretically homogeneous preparations of cellobiase I and cellobiase II have been obtained. By means of gel-filtration their molecular weights have been estimated to be 140,000 and 67,000. Cellobiase I consists of five and cellobiase II of two polypeptide chains. Three cellulases with various ratios of endoglucanase and exoglucosidase activities have been prepared. Using polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, their molecular weights have been found to be 11,600; 10,900 and 11,200.

Aspergillus↗
PubMedDate not supplied

[Selection of Trichoderma viride, a producer of cellulase].

A mutant strain of Trichoderma viride producing cellulase has been obtained as a result of three-stage selection using chemical and physical factors. New variants with modified characteristics appeared after the action of nitroso compounds on a suspension of conidia at the first stage of selection and the action of temperature at the second stage. The new characteristics were intensified and became stable at the third stage of selection. The experimental mutagenesis yielded an active an active mutant of Trichoderma viride 44 which synthesized cellulase (up to 22 units/ml) four times better than the parent culture Trichoderma viride F-57.

Aziridines↗
PubMed1980

[New ultrasonic method for studying the composition and properties of multienzyme systems: enzymes of the cellulase complex].

A new ultrasonic method for determination of the composition and properties of individual components of multienzyme systems without their resolution has been developed. The method is based on a determination of the pH-profiles of the first order rate constants for inactivation of the enzymatic components in a complex by ultrasonic cavitation. The method was used for studying a cellulase complex from Geotrichum candidum. It was shown that the cellulase complex contains at least four cellulolytic enzymes, i. e. endoglucanase, exoglucosidase, cellobiase and aryl-beta-glucosidase, which differ in their pK values for the ionogenic groups controlling the pH-profiles of ultrasonic inactivation and in the inactivation rate constants at the plateau of a pH-rate profile.

Cellulase↗
PubMed1994

Statistic method for determining the fusion-recombination of cellulase genome.

A hypothesis was proposed based on cellulase synergism and multiple variable statistics that the experimental value of N strains out of total fusants from the same cell fusion pool, Aspergillus niger x Trichoderma reesei, could be a sample for the definite fusion cross due to the independence and random of DNA recombination. It could be reduced if fusion recombination happened by analyzing the sample with the provided computer program selected 40 strains of about 2000 fusants of A. niger x T. reesei were analyzed under this procedure as an example and was showed that was effective method on guiding cellulase breeding.

Aspergillus niger↗
PubMed1994

Papain digestion of crude Trichoderma reesei cellulase: purification and properties of cellobiohydrolase I and II core proteins.

The major cellulase components produced by Trichoderma reesei are composed of distinct catalytic and cellulose-binding domains. A simple two-step procedure is described for the purification of the catalytic domains, also termed core proteins (cp), of the major components, cellobiohydrolase (CBH) I and II. The novel aspect of this procedure is that native CBH I and II do not have to be purified initially. Papain digestion of a commercial T. reesei cellulase preparation followed by gel filtration on a Superdex 75 column resulted in the separation of fractions containing CBH I cp and CBH II cp; chromatofocusing purified the latter to homogeneity. N-terminal protein sequencing of CBH II cp provided good evidence for its identity. A comparison of the catalytic activity and cellulose-binding ability of these cp was made. A major difference between them was that CBH II cp bound to microcrystalline cellulose, unlike CBH I cp. CBH I cp readily hydrolysed the bond between the aglycone and cellobiose in p-nitrophenyl cellobioside unlike the CBH II cp preparation. Neither CBH I cp nor CBH II cp had activity toward carboxymethylcellulose, but both were able to hydrolyse barley beta-glucan. It was also shown that incubation of cellulose fibres with native CBH I, CBH I cp or CBH II cp resulted in a smoothing of the fibre surface.

Adsorption↗
PubMed1997

Studies on cellulases of Aspergillus nidulans mutants.

Mutants were characterized as to their morphology, auxotrophy and cellulase production. No apparent correlation was evident among these characters. The degree of repression or enhancement of the three components of the cellulase enzyme in the mutants varied considerably, indicating their separate genetic control. Considerable variations in the enzyme profiles of the mutants were observed as compared to the wild type. Enzyme production was also found to be related to development.

Aspergillus nidulans↗
PubMed1998

Hydrolysis of cellulose using ternary mixtures of purified cellulases.

The saccharification of microcrystalline cellulose by reconstituted ternary mixtures of purified cellulases (one endoglucanase and two cellobiohydrolases) has been studied over the entire range of mixture compositions. Ternary plots are used to compare the performance of five synthetic mixtures drawn from the cellulase systems of Acidothermus cellulolyticus, Trichoderma reesei, Thermomonospora fusca, and Thermotoga neapolitana. Results reveal that at least one synthetic mixture utilizing enzymes from three different organisms delivers performance competitive with that of a "native" (i.e., co-evolved) ternary system drawn exclusively from T. reesei. This heterologous system, consisting of the endoglucanase E1 from A. cellulolyticus and the exoglucanases CBHI from T. reesei and E3 from T. fusca, is forgiving from the system-design point of view, in that it delivers high saccharification rates over a wide range of mixture compositions.

Aspergillus niger↗
PubMedDate not supplied

Influence of different cultural conditions on cellulase production by Nectria catalinensis.

The production of the extracellular cellulolytic enzyme system (endoglucanase, exoglucanase and cellobiase) of N. catalinensis was tested with different nitrogen sources, inorganic and organic ones, in liquid culture medium with microcrystalline cellulose. The nitrogen compounds used were: potassium nitrate, sodium nitrate, ammonium nitrate, ammonium phosphate, ammonium sulphate, ammonium chloride, ammonium carbonate, ammonium acetate, ammonium tartrate, urea, casamino acids, glycine, L-alanine, L-leucine, L-proline, L-lysine, L-aspartic acid, L-glutamic acid, L-asparagine, L-glutamine, L-phenylalanine, L-tyrosine, L-tryptophan, L-methionine and L-cysteine. Among these, ammonium nitrate and ammonium tartrate gave the highest yields of cellulases in 20-day-old cultures at a concentration equivalent to 0.75 g N/l in both cases. Optimal temperature for cellulase production, growth and cellulose degradation was 23 degrees C. On the other hand, an initial pH of 6.5 gave the highest yields of endoglucanase and cellobiase. In the same way, at pH 6.5, maximal growth and cellulose degradation were achieved. However, maximal exoglucanase production and glycogen content were reached at pH 7.5.

Amino Acids↗
PubMed2001

The catalytic domain of a Piromyces rhizinflata cellulase expressed in Escherichia coli was stabilized by the linker peptide of the enzyme.

Analysis of a carboxymethyl-cellulase clone isolated from the cDNA library of the ruminal fungus, Piromyces rhizinflata 2301, revealed that the clone encoded a polypeptide containing a cellulase catalytic domain, designated CelAcd. CelAcd was flanked by a 28-amino acid linker peptide at the N-terminus and linked to a dockerin domain by a 7-amino acid linker at the C-terminus. CelAcd showed homology with the family 5 of glycosyl hydrolases. CelAcd plus the linker peptides at both termini (designated CelcdN'C') was expressed in Escherichia coli and the purified enzyme was characterized. The feature of particular interest of CelcdN'C' was its bifunctional endo- and exo-glucanase activity, demonstrated by its ability to hydrolyse carboxymethyl cellulose (CMC) and pNP-beta-D-cellobioside. Furthermore, CelcdN'C' exhibited relatively high ability to degrade both microcrystalline Avicel and filter paper. CelcdN'C' also showed activity against barley beta-glucan, Lichenin and oat spelt xylan. The optimal activity conditions for CelcdN'C' with CMC as the substrate were pH 5.5 and 50 degrees C. Fifty percent of the enzyme activity was lost when CelcdN'C' was treated at 55 degrees C for 10 min. CelcdN'C' retained more than 10% enzyme activity after being heated under 90 degrees C for 10 min. Deletion of the N-terminal flanking linker of CelcdN'C' (the resulting protein was designated CelcdC') did not alter the enzymatic function of the catalytic domain. However, the thermal stability of CelcdC' was dramatically reduced. We conclude that the N-terminal flanking linker of CelAcd stabilizes the enzyme protein.

Journal Article↗
PubMed2001

Thermostable, alkalophilic and cellulase free xylanase production by Thermoactinomyces thalophilus subgroup C.

Thermoactinomyces thalophilus produced cellulase free extracellular endo-1,4-beta-xylanase (EC 3.2.1.8) at 50 degrees C and pH 8.5. Maximum xylanase production was achieved in fermentation medium using birchwood xylan as substrate after 96 h of growth at 50 degrees C. Other agricultural substrates such as wheat bran, wheat straw, sugarcane bagasse and cornstover produced less xylanase. The crude enzyme preparation from mutant T. thalophilus P2 grown under optimised fermentation conditions showed no cellulase contamination and maximum xylanase activity of 42 U/ml at 65%deg;C and pH 8.5-9.0. This enzyme with initial xylanase activity of 42 U/ml was found thermostable up to 65 degrees C and retaining 50% of its activity after its incubation for 125 min at 65 degrees C.

Journal Article↗