scholarly journals Studies of the cellulolytic system of the filamentous fungus Trichoderma reesei QM 9414. Substrate specificity and transfer activity of endoglucanase I

1990 ◽  
Vol 270 (1) ◽  
pp. 251-256 ◽  
Author(s):  
M Claeyssens ◽  
H van Tilbeurgh ◽  
J P Kamerling ◽  
J Berg ◽  
M Vrsanska ◽  
...  
Keyword(s):  
Trichoderma Reesei ◽  
Filamentous Fungus ◽  
Substrate Concentration ◽  
Formation Rate ◽  
Transfer Reactions ◽  
Main Reaction ◽  
Reaction Products ◽  
Transfer Product ◽  
Endoglucanase I ◽  
Glucose Formation

Endoglucanase I from the filamentous fungus Trichoderma reesei catalyses hydrolysis and glycosyl-transfer reactions of cello-oligosaccharides. Initial bond-cleaving frequencies determined with 1-3H-labelled cello-oligosaccharides proved to be substrate-concentration-dependent. Using chromophoric glycosides and analysing the reaction products by h.p.l.c., kinetic data are obtained and, as typical for an endo-type depolymerase, apparent hydrolytic parameters (kcat., kcat./Km) increase steadily as a function of the number of glucose residues. At high substrate concentrations, and for both free cellodextrins and their aromatic glycosides, complex patterns (transfer reactions) are, however, evident. In contrast with the corresponding lactosides and 1-thiocellobiosides, and in conflict with the expected specificity, aromatic 1-O-beta-cellobiosides are apparently hydrolysed at both scissile bonds, yielding the glucoside as one of the main reaction products. Its formation rate is clearly non-hyperbolically related to the substrate concentration and, since the rate of D-glucose formation is substantially lower, strong indications for dismutation reactions (self-transfer) are again obtained. Evidence for transfer reactions catalysed by endoglucanase I further results from experiments using different acceptor and donor substrates. A main transfer product accumulating in a digest containing a chromophoric 1-thioxyloside was isolated and its structure elucidated by proton n.m.r. spectrometry (500 MHz). The beta 1-4 configuration of the newly formed bond was proved.

scholarly journals Dimethyl Ether to Olefins over Modified ZSM-5 Based Catalysts Stabilized by Hydrothermal Treatment

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 485 ◽  
Author(s):  
Maria Magomedova ◽  
Ekaterina Galanova ◽  
Ilya Davidov ◽  
Mikhail Afokin ◽  
Anton Maximov
Keyword(s):  
Steady State ◽  
Hydrothermal Treatment ◽  
Dimethyl Ether ◽  
Formation Rate ◽  
Reaction Rates ◽  
Product Formation ◽  
Acid Sites ◽  
Weak Acid ◽  
Main Reaction ◽  
Reaction Products

The reaction of dimethyl ether to olefin over HZSM-5/Al2O3 catalysts modified by Zr and Mg and stabilized by hydrothermal treatment has been studied. Regardless of the introduction method and the nature of the metal, the dependence of the key products selectivity on X(DME) over hydrothermally treated steady-state catalysts does not change, and the experimental points are described by the same curves. Metal introduction and the corresponding changes in the acid sites distribution do not change the ratio of main reaction rates, only the absolute values of the formation rate of the products are changed. Zr doping leads to the greatest activity in the DME conversion due to an equable decrease in the total acidity of the sample. On the other hand, the Mg-modified sample has a higher amount of weak acid sites, which reduces activity. At low DME conversion, methanol is one of the primary reaction products which formed from DME simultaneously with propylene in alkene cycle. At high DME conversion, the methanol acts as a main reagent which leads to ethylene formation in the arene cycle. Based on the results, the role of the metal in the reaction chemistry is considered and the mechanism of product formation from DME over steady-state catalyst is proposed, which describes both the participation of DME and the methanol produced.

scholarly journals cAMP activates calcium signalling via phospholipase C to regulate cellulase production in the filamentous fungus Trichoderma reesei

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Yumeng Chen ◽  
Xingjia Fan ◽  
Xinqing Zhao ◽  
Yaling Shen ◽  
Xiangyang Xu ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Phospholipase C ◽  
Trichoderma Reesei ◽  
Filamentous Fungus ◽  
Calcium Signalling ◽  
Signal Transduction Pathway ◽  
Cellulase Production ◽  
Signalling Pathway ◽  
Dependent Manner ◽  
Transduction Pathway

Abstract Background The filamentous fungus Trichoderma reesei is one of the best producers of cellulase and has been widely studied for the production of cellulosic ethanol and bio-based products. We previously reported that Mn2+ and N,N-dimethylformamide (DMF) can stimulate cellulase overexpression via Ca2+ bursts and calcium signalling in T. reesei under cellulase-inducing conditions. To further understand the regulatory networks involved in cellulase overexpression in T. reesei, we characterised the Mn2+/DMF-induced calcium signalling pathway involved in the stimulation of cellulase overexpression. Results We found that Mn2+/DMF stimulation significantly increased the intracellular levels of cAMP in an adenylate cyclase (ACY1)-dependent manner. Deletion of acy1 confirmed that cAMP is crucial for the Mn2+/DMF-stimulated cellulase overexpression in T. reesei. We further revealed that cAMP elevation induces a cytosolic Ca2+ burst, thereby initiating the Ca2+ signal transduction pathway in T. reesei, and that cAMP signalling causes the Ca2+ signalling pathway to regulate cellulase production in T. reesei. Furthermore, using a phospholipase C encoding gene plc-e deletion strain, we showed that the plc-e gene is vital for cellulase overexpression in response to stimulation by both Mn2+ and DMF, and that cAMP induces a Ca2+ burst through PLC-E. Conclusions The findings of this study reveal the presence of a signal transduction pathway in which Mn2+/DMF stimulation produces cAMP. Increase in the levels of cAMP activates the calcium signalling pathway via phospholipase C to regulate cellulase overexpression under cellulase-inducing conditions. These findings provide insights into the molecular mechanism of the cAMP–PLC–calcium signalling pathway underlying cellulase expression in T. reesei and highlight the potential applications of signal transduction in the regulation of gene expression in fungi.

Efficient Production of Antibody Fragments by the Filamentous Fungus Trichoderma reesei

1993 ◽  
Vol 11 (5) ◽  
pp. 591-595 ◽  
Author(s):  
Eini Nyyssönen ◽  
Merja Penttilä ◽  
Anu Harkki ◽  
Anu Saloheimo ◽  
Jonathan K. C. Knowles ◽  
...  
Keyword(s):  
Trichoderma Reesei ◽  
Filamentous Fungus ◽  
Antibody Fragments ◽  
Efficient Production

scholarly journals Use of Coal Bottom Ash and CaO-CaCl2-Activated GGBFS Binder in the Manufacturing of Artificial Fine Aggregates through Cold-Bonded Pelletization

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5598
Author(s):  
Dongho Jeon ◽  
Woo Sung Yum ◽  
Haemin Song ◽  
Seyoon Yoon ◽  
Younghoon Bae ◽  
...  
Keyword(s):  
Early Stage ◽  
Bottom Ash ◽  
Relative Weight ◽  
Main Reaction ◽  
Reaction Products ◽  
Coal Bottom Ash ◽  
Heavy Metal Leaching ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Cementless Binder

This study investigated the use of coal bottom ash (bottom ash) and CaO-CaCl2-activated ground granulated blast furnace slag (GGBFS) binder in the manufacturing of artificial fine aggregates using cold-bonded pelletization. Mixture samples were prepared with varying added contents of bottom ash of varying added contents of bottom ash relative to the weight of the cementless binder (= GGBFS + quicklime (CaO) + calcium chloride (CaCl2)). In the system, the added bottom ash was not simply an inert filler but was dissolved at an early stage. As the ionic concentrations of Ca and Si increased due to dissolved bottom ash, calcium silicate hydrate (C-S-H) formed both earlier and at higher levels, which increased the strength of the earlier stages. However, the added bottom ash did not affect the total quantities of main reaction products, C-S-H and hydrocalumite, in later phases (e.g., 28 days), but simply accelerated the binder reaction until it had occurred for 14 days. After considering both the mechanical strength and the pelletizing formability of all the mixtures, the proportion with 40 relative weight of bottom ash was selected for the manufacturing of pilot samples of aggregates. The produced fine aggregates had a water absorption rate of 9.83% and demonstrated a much smaller amount of heavy metal leaching than the raw bottom ash.

scholarly journals Hot Corrosion Behavior of BaLa2Ti3O10 Thermal Barrier Ceramics in V2O5 and Na2SO4 + V2O5 Molten Salts

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 351 ◽  
Author(s):  
Hui Liu ◽  
Jin Cai ◽  
Jihong Zhu
Keyword(s):  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Molten Salts ◽  
Main Reaction ◽  
Thermal Barrier ◽  
Dense Layer ◽  
Reaction Products ◽  
Corrosion Medium ◽  
Barrier Coating ◽  
Salt Corrosion

BaLa2Ti3O10 ceramics for thermal barrier coating (TBC) applications were fabricated, and exposed to V2O5 and Na2SO4 + V2O5 molten salts at 900 °C to investigate the hot corrosion behavior. After 4 h corrosion tests, the main reaction products resulting from V2O5 salt corrosion were LaVO4, TiO2, and Ba3V4O13, whereas those due to Na2SO4 + V2O5 corrosion consisted of LaVO4, TiO2, BaSO4 and some Ba3V4O13. The structures of reaction layers on the surfaces depended on the corrosion medium. In V2O5 salt, the layer was dense and had a thickness of 8–10 μm. While in Na2SO4 + V2O5 salt, it had a ~15 μm porous structure and a dense, thin band at the bottom. Beneath the dense layer or the band, no obvious molten salt was found. The mechanisms by which the reaction layer forms were discussed.

scholarly journals Mode of action of endoglucanase III from Trichoderma reesei

1993 ◽  
Vol 289 (3) ◽  
pp. 867-873 ◽  
Author(s):  
R Macarrón ◽  
C Acebal ◽  
M P Castillón ◽  
J M Domínguez ◽  
I de la Mata ◽  
...  
Keyword(s):  
New Orleans ◽  
Trichoderma Reesei ◽  
Culture Medium ◽  
Ph Dependence ◽  
Maximal Activity ◽  
Cleavage Sites ◽  
Reaction Products ◽  
Binding Model ◽  
Independent Evidence ◽  
Affinity Labelling

Endoglucanase III (EG III) was purified to homogeneity from the culture medium of Trichoderma reesei QM 9414. It has a molecular mass of 48 kDa, and an isoelectric point of 5.1. Maximal activity was observed between pH4 and 5. Celloligosaccharides and their chromophoric derivatives were used as substrates, and the reaction products were analysed by quantitative h.p.l.c. Nucleophilic competition experiments (between methanol and water) allowed unequivocal assessment of cleavage sites. EG III preferentially released cellobiose (or the corresponding glycoside) from the reducing end of the higher cellodextrins. A putative binding model containing five subsites is proposed. The pH-dependence of 4′-methylumbelliferyl beta-cellotrioside hydrolysis indicates the presence of a protonated group with a pK 5.5 in the reaction mechanism, and the possible involvement of a carboxy group is corroborated by a temperature study (delta Hion = -15.9 J/mol). This, together with independent evidence from affinity-labelling experiments [Tomme, Macarrón and Claeyssens (1991) Cellulose '91, New Orleans, Abstr. 32] and n.m.r. studies [Gebbler, Gilkes, Claeyssens, Wilson, Béguin, Wakarchuk, Kilburn, Miller, Warren and Withers (1992) J. Biol. Chem. 267, 12559-12561], favours the assumption of a lysozyme-type (retention of configuration, two essential carboxy groups) mechanism for this family A cellulase.

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