PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Trichoderma”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources
PubMed1991

Ethylene Biosynthesis-Inducing Xylanase : II. Purification and Physical Characterization of the Enzyme Produced by Trichoderma viride.

The ethylene biosynthesis-inducing endoxylanase (EIX) from xylan-induced cultures of the fungus, Trichoderma viride, was purified to near homogeneity and compared with the EIX isolated from Cellulysin. Both enzymes migrate as 9.2 kilodalton proteins during gel filtration chromatography under nondenaturing conditions, but the mature polypeptide migrates as a 22 kilodalton band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition of the 22 kilodalton polypeptide is enriched by Gly, Ser, Thr, Trp, and Tyr, but depleted in Ala, Glx, Leu, and Lys. Both proteins lack sulfur-containing amino acids. The protein is glycosylated, and inhibition of EIX synthesis by tunicamycin suggests that at least some of the sugar moieties are linked to asparagine residues. EIX appears to be synthesized initially as a 25 kilodalton precursor protein that is processed to 22 kilodalton during secretion.

Journal Article↗
PubMed1966

Morphogenesis in Trichoderma: suppression of photoinduction by 5-fluorouracil.

Sporulation in the fungus Trichoderma viride is inducible with a short light pulse. 5-Fluorouracil applied prior to photoinduction and removed thereafter suppressed sporulation without greatly aflecting growth. This compound also halved the rate of incorporation of uracil-C(14) into RNA but did not change the ratio of uridylic to cytidylic acid. The effect of 5-fluorouracil was counteracted by uracil but not by thymidine. This supports the hypothesis that 5-fluorouracil affects RNA rather than DNA.

Carbon Isotopes↗
PubMed1966

Malathion degradation by Trichoderma viride and a Pseudomonas species.

Malathion was found to be metabolized quickly by a soil fungus, Trichoderma viride, and a bacterium, Pseudomonas sp., which were originally found in soils from northern Ohio that had been sprayed heavily with insecticides. Results of a survey of the breakdown capabilities of 16 variants of T. viride revealed that certain colonies from this species had a very marked ability to breakdown malathion through the action of a carboxylesterase(s). The enzymes can be made soluble by preparing the acetone powder suspension.

Carbon Isotopes↗
PubMed1977

Semiquantitative Plate Assay for Determination of Cellulase Production by Trichoderma viride.

A plate clearing assay was devised to screen for high-producing cellulase mutants of Trichoderma viride. The method employs (i) the use of either rose bengal or oxgall to limit colony size and (ii) Phosfon D (tributyl-2, 4-dichloroben-zylphosphonium chloride) to enhance cellulase detection, in combination with acid-swollen cellulose on agar plates. The method was used to isolate constitutive cellulase mutants of T. viride and should prove useful for isolating high-producing mutants from a range of organisms. This technique has been also used to determine the concentration at which glucose and glycerol inhibit cellulase synthesis by catabolite repression in the wild-type strains.

Journal Article↗
PubMed1981

Comparison of Extracellular Cellulase Activities of Clostridium thermocellum LQRI and Trichoderma reesei QM9414.

The crude extracellular cellulase of Clostridium thermocellum LQRI (virgin strain) was very active and solubilized microcrystalline cellulose at one-half the rate observed for the extracellular cellulase of Trichoderma reesei QM9414 (mutant strain). C. thermocellum cellulase activity differed considerably from that of T. reesei as follows: higher endoglucanase/exoglucanase activity ratio; absence of extracellular cellobiase or beta-xylosidase activity; long-chain oligosaccharides instead of short-chain oligosaccharides as initial (15-min) hydrolytic products on microcrystalline cellulose; mainly cellobiose or xylobiose as long-term (24-h) hydrolysis products of Avicel and MN300 or xylan; and high activity and stability at 60 to 70 degrees C. Under optimized reaction conditions, the kinetic properties (V(max), 0.4 mumol/min per mg of protein; energy of activation, 33 kJ; temperature coefficient, 1.8) of C. thermocellum cellulose-solubilizing activity were comparable to those reported for T. reesei, except that the dyed Avicel concentration at half-maximal velocity was twofold higher (182 muM). The cellulose-solubilizing activity of the two crude cellulases differed considerably in response to various enzyme inhibitors. Most notably, Ag and Hg effectively inhibited C. thermocellum but not T. reesei cellulase at <20 muM, whereas Ca, Mg, and Mn inhibited T. reesei but not C. thermocellum cellulase at >10 mM. Both enzymes were inhibited by Cu (>20 mM), Zn (>1.0 mM), and ethylene glycol-bis(beta-aminoethyl ether)- N,N-tetraacetic acid (>10 mM). T. reesei but not C. thermocellum cellulose-solubilizing activity was 20% inhibited by glucose (73 mM) and cellobiose (29 mM). Both cellulases preferentially cleaved the internal glycosidic bonds of cellooligosaccharides. The overall rates of cellooligosaccharide degradation were higher for T. reesei than for C. thermocellum cellulase, except that the rates of conversion of cellohexaose to cellotriose were equivalent.

Journal Article↗
PubMed1984

Protoplast Fusion of Trichoderma reesei, Using Immature Conidia.

Protoplast fusion of strains derived from Trichoderma reesei QM9414 and QM9136 and the segregation of the resulting fusants were studied. Combinations of protoplasts prepared from young conidia with double amino acid requirements, one of which was a common requirement and the other uncommon, were fused in the presence of polyethylene glycol 6000. Fusants were selected as regenerant colonies requiring only the commonly deficient amino acid. The frequency of fusion was 0.9 x 10 to 4.0 x 10 for the starting conidia and 3.0 x 10 to 4.9 x 10 for the regenerated protoplasts, which was significantly higher than the expected reversion frequencies by mutation. Conidia generated on the fusant colonies showed diverse phenotypes, i.e., parental types (40 to 80%) and nonparental types (20 to 60%). Colonies developed from single conidia of the nonparental phenotype contained special spots called "knobs" that have a higher density of mycelia. The phenotype of the knobs was again varied among prototrophs, parental types, and recombinant types; and their traits were inherited stably. The phenotype of the mycelia in the nonknob part was essentially the same as that of the original conidia and again formed knobs in colonies upon transfer of a piece of mycelia to a fresh medium. The conidial DNA content of the knob clone was almost the same as that of the parents, but that of the fusants was 1.2 to 2.0 times higher than that of the parents. From these results, we conclude that knobs are the segregants from the fusants. One knob clone showed twice the carboxymethyl cellulose hydrolyzing activity of the parents, suggesting the possibility of breeding T. reesei cells by the protoplast fusion technique.

Journal Article↗
PubMed1985

Solid-State Fermentation with Trichoderma reesei for Cellulase Production.

Cellulase yields of 250 to 430 IU/g of cellulose were recorded in a new approach to solid-state fermentation of wheat straw with Trichoderma reesei QMY-1. This is an increase of ca. 72% compared with the yields (160 to 250 IU/g of cellulose) in liquid-state fermentation reported in the literature. High cellulase activity (16 to 17 IU/ml) per unit volume of enzyme broth and high yields of cellulases were attributed to the growth of T. reesei on a hemicellulose fraction during its first phase and then on a cellulose fraction of wheat straw during its later phase for cellulase production, as well as to the close contact of hyphae with the substrate in solid-state fermentation. The cellulase system obtained by the solid-state fermentation of wheat straw contained cellulases (17.2 IU/ml), beta-glucosidase (21.2 IU/ml), and xylanases (540 IU/ml). This cellulase system was capable of hydrolyzing 78 to 90% of delignified wheat straw (10% concentration) in 96 h, without the addition of complementary enzymes, beta-glucosidase, and xylanases.

Journal Article↗
PubMed1985

Effect of Colloidal Materials on Cellulase Production by Trichoderma reesei Rut-C30.

The addition of positively charged colloidal materials to the growth medium markedly increased the concentration of cellulase enzymes produced by Trichoderma reesei Rut-C30. Filter paper activities of up to 4 and 13 IU/ml have been achieved by the addition of colloidal materials, using 3% lactose and 3% cellulose, respectively, as a substrate. The particles exert their effect by binding soluble sugars and slowing their uptake by the organism.

Journal Article↗
PubMed1987

Ethanol Perturbs Glycosylation and Inhibits Hypersecretion in Trichoderma reesei.

The effects of ethanol and phenylethanol on the growth of and glycoprotein secretion by Trichoderma reesei were studied. Low levels (1.5%, vol/vol) of ethanol perturbed the glycosylation process, as shown by alterations in the isoelectric profile of the secreted proteins and a reduction in the rate of incorporation of mannose into oligosaccharides. In addition to these effects on posttranslational modification, ethanol drastically lowered the protein secretion level of a hypersecretory strain.

Journal Article↗
PubMed1989

Purification and Characterization of an Endo-(1,3)-beta-d-Glucanase from Trichoderma longibrachiatum.

A laminarinase [endo-(1,3)-beta-d-glucanase] has been purified from Trichoderma longibrachiatum cultivated with d-glucose as the growth substrate. The enzyme was found to hydrolyze laminarin to oligosaccharides varying in size from glucose to pentaose and to lesser amounts of larger oligosaccharides. The enzyme was unable to cleave laminaribiose but hydrolyzed triose to laminaribiose and glucose. The enzyme cleaved laminaritetraose, yielding laminaritriose, laminaribiose, and glucose, and similarly cleaved laminaripentaose, yielding laminaritetraose, laminaritriose, laminaribiose, and glucose. The enzyme cleaved only glucans containing beta-1,3 linkages. The pH and temperature optima were 4.8 and 55 degrees C, respectively. Stability in the absence of a substrate was observed at temperatures up to 50 degrees C and at pH values between 4.9 and 9.3. The molecular mass was determined to be 70 kilodaltons by sodium dodecyl sulfate-12.5% polyacrylamide gel electrophoresis, and the pI was 7.2. Enzyme activity was significantly inhibited in the presence of HgCl(2), MnCl(2), KMnO(4), and N-bromosuccinimide. The K(m) of the enzyme on laminarin was 0.0016%, and the V(max) on laminarin was 3,170 mumol of glucose equivalents per mg of the pure enzyme per min.

Journal Article↗
PubMed1990

Transfer of Isolated Nuclei into Protoplasts of Trichoderma harzianum.

Protoplasts released from young hyphae of Trichoderma harzianum contained 0 to 10 nuclei per protoplast, and most (about 80%) contained from 4 to 6 nuclei. Most protoplasts were larger than 3 mum in diameter. Nuclei were isolated from protoplasts of an auxotrophic mutant of T. harzianum and transferred into protoplasts obtained from another auxotroph of the same strain. This intrastrain nuclear transfer gave rise to numerous progeny which were stable, prototrophic, and heterokaryotic. Interstrain transfers in which nuclei from a wild-type prototroph of one strain were transferred into protoplasts from a lysine-deficient auxotroph of a second strain were also done. Heterokaryotic progeny were recovered from these interstrain transfers when the regenerating protoplasts were provided with a low concentration of lysine 48 h after the initial plating. Heterokaryotic progeny contained 11 to 17% of donor-type nuclei. Progeny homokaryotic for donor-type nuclei were obtained as single-spore isolates. These homokaryotic isolates expressed the isozyme pattern and colony morphology phenotype of the nuclear donor. When regenerating protoplasts were provided with lysine 10 days after the initial plating, only a single progeny was obtained. However, single-spore subprogeny of this nuclear transfer were prototrophic and exhibited a wide range of unstable morphological phenotypes.

Journal Article↗
PubMed1990

Interrelationship of Xylanase Induction and Cellulase Induction of Trichoderma longibrachiatum.

Xylose oligomers rapidly induced xylanase activity of Trichoderma longibrachiatum, whereas induction was delayed in the presence of glucose. Cellobiose, cellopentaose, and xylobiose did not induce detectable levels of cellulase activity. However, mixtures of xylobiose with cellobiose or cellopentaose rapidly induced cellulase activity. In addition, mixtures of xylobiose with cellopentaose or cellobiose induced xylanase activity more effectively than xylobiose alone. Both xylanase and cellulase activity were detected after a lag period in the presence of lactose.

Journal Article↗
PubMed1991

Carbon Source Control of Cellobiohydrolase I and II Formation by Trichoderma reesei.

Regulation of the formation and secretion of two cellulase components from Trichoderma reesei QM 9414, cellobiohydrolases I and II (CBH I and CBH II, respectively), by the carbon source was investigated. With monoclonal antibodies against CBH I and CBH II it was found that during cultivation on carbon sources which enable fast growth (glucose, glycerol, and fructose), no formation of CBH I occurred, whereas low levels of CBH II were formed. Lactose and cellulose, which allow comparably slower growth, promoted the formation of both CBH I and CBH II. However, noncarbohydrate carbon sources as citrate or acetate, which also enable only slow growth, did not promote the formation of CBH I or CBH II. The addition of glucose or glycerol to lactose- or cellulose-pregrown mycelia, on the other hand, only partially reduced the formation of CBH I. This reduction was also achieved by several other metabolizable and nonmetabolizable carbon compounds, e.g., fructose, galactose, beta-methylglucoside, 2-deoxyglucose, and rhamnose, as well as by transfer to no carbon source at all. This result indicates that the control of CBH I synthesis by the carbon source is due to induction and not to repression. The use of cycloheximide and 5-fluorouracil as inhibitors at and before translation, respectively, revealed a half-life for CBH I mRNA of at least several hours, which may, at least in part, account for the prolonged synthesis of some CBH I under these conditions. Northern (RNA) hybridization with full copies of cbh1 and cbh2 genes indicated that the control of CBH I and CBH II biosyntheses by the carbon source operates mainly at the pretranslational level. We conclude that the low rate of cellulase synthesis on glucose and some other carbon sources is due to the lack of an inducer and not to carbon source repression.

Journal Article↗
PubMed1996

The Cellulases Endoglucanase I and Cellobiohydrolase II of Trichoderma reesei Act Synergistically To Solubilize Native Cotton Cellulose but Not To Decrease Its Molecular Size.

Degradation of cotton cellulose by Trichoderma reesei endoglucanase I (EGI) and cellobiohydrolase II (CBHII) was investigated by analyzing the insoluble cellulose fragments remaining after enzymatic hydrolysis. Changes in the molecular-size distribution of cellulose after attack by EGI, alone and in combination with CBHII, were determined by size exclusion chromatography of the tricarbanilate derivatives. Cotton cellulose incubated with EGI exhibited a single major peak, which with time shifted to progressively lower degrees of polymerization (DP; number of glucosyl residues per cellulose chain). In the later stages of degradation (8 days), this peak was eventually centered over a DP of 200 to 300 and was accompanied by a second peak (DP, (apprx=)15); a final weight loss of 34% was observed. Although CBHII solubilized approximately 40% of bacterial microcrystalline cellulose, the cellobiohydrolase did not depolymerize or significantly hydrolyze native cotton cellulose. Furthermore, molecular-size distributions of cellulose incubated with EGI together with CBHII did not differ from those attacked solely by EGI. However, a synergistic effect was observed in the reducing-sugar production by the cellulase mixture. From these results we conclude that EGI of T. reesei degrades cotton cellulose by selectively cleaving through the microfibrils at the amorphous sites, whereas CBHII releases soluble sugars from the EGI-degraded cotton cellulose and from the more crystalline bacterial microcrystalline cellulose.

Journal Article↗
PubMed1997

Expression and Secretion of Barley Cysteine Endopeptidase B and Cellobiohydrolase I in Trichoderma reesei.

Localization of expression and secretion of a heterologous barley cysteine endopeptidase (EPB) and the homologous main cellobiohydrolase I (CBHI) in a Trichoderma reesei transformant expressing both proteins were studied. The transformant was grown on solid medium with Avicel cellulose and lactose to induce the cbh1 promoter for the synthesis of the native CBHI and the recombinant barley protein linked to a cbh1 expression cassette. Differences in localization of expression between the two proteins were clearly indicated by in situ hybridization, indirect immunofluorescence, and immunoelectron microscopy. In young hyphae, native-size recombinant epb mRNA was localized to apical compartments. In older cultures, it was also seen in subapical compartments but not in hyphae from the colony center. The recombinant EPB had a higher molecular weight than the native barley protein, probably due to glycosylation and differential processing in the fungal host. As was found with its transcripts, recombinant EPB was localized in apical and subapical compartments of hyphae. The cbh1 mRNA and CBHI were both localized to all hyphae of a colony, which suggests that the endogenous CBHI was also secreted from these. In immunoelectron microscopy, the endoplasmic reticulum and spherical vesicles assumed to contribute to secretion were labeled by both CBHI and EPB antibodies while only CBHI was localized in elongated vesicles close to the plasma membrane and in hyphal walls. The results indicate that in addition to young apical cells, more mature hyphae in a colony may secrete proteins.

Journal Article↗
PubMed1997

Expression of Barley Endopeptidase B in Trichoderma reesei.

The gene for barley endopeptidase B (EPB) has been expressed in the filamentous fungus Trichoderma reesei from the cbh1 promoter. The EPB signal sequence allowed secretion of over 90% of the recombinant protein. Yields reached about 500 mg of immunoreactive protein per liter and exceeded values for any other protein derived from a higher eukaryotic organism produced in T. reesei.

Journal Article↗
PubMed1997

Cellular and Molecular Mechanisms Involved in the Interaction between Trichoderma harzianum and Pythium ultimum.

The interaction between Trichoderma harzianum and the soilborne plant pathogen Pythium ultimum was studied by electron microscopy and further investigated by gold cytochemistry. Early contact between the two fungi was accompanied by the abnormal deposition of a cellulose-enriched material at sites of potential antagonist penetration. The antagonist displayed the ability to penetrate this barrier, indicating that cellulolytic enzymes were produced. However, the presence of cellulose in the walls of severely damaged Pythium hyphae indicated that cellulolytic enzymes were not the only critical traits involved in the antagonistic process. The marked alteration of the (beta)-1,3-glucan component of the Pythium cell wall suggested that (beta)-1,3-glucanases played a key role in the process.

Journal Article↗