Trichoderma reesei

About: Trichoderma reesei is a research topic. Over the lifetime, 3832 publications have been published within this topic receiving 152877 citations. The topic is also known as: Trichoderma reesi.

Novel CBH1 Homologs And Variant CBH1 Cellulases

Abstract: Disclosed are a number of homologs and variants of Hypocrea jecorina Cel7A (formerly Trichoderma reesei cellobiohydrolase I or CBH1), nucleic acids encoding the same and methods for producing the same. The homologs and variant cellulases have the amino acid sequence of a glycosyl hydrolase of family 7A wherein one or more amino acid residues are substituted and/or deleted.

Xylanase production by fungal mixed culture solid substrate fermentation on sugar cane bagasse

Abstract: Trichoderma reesei was co-cultured with either Aspergillus niger or A. phoenicis in solid substrate fermentation on sugar cane bagasse for xylanase production. When soymeal was used as nitrogen supplement, optimal activities of cellulase (14-15 IU/g dry wt) and xylanase (2,600-2,800 IU/g dry wt) were attained by both mixed culture systems in 72 h of fermentation, corresponding to xylanase volumetric productivities of 5,500-5,900 lU/L.h.

High Production of β-Glucosidase in Schizophyllum commune: Isolation of the Enzyme and Effect of the Culture Filtrate on Cellulose Hydrolysis

Abstract: Optimization experiments with response surface statistical analysis were performed with Schizophyllum commune to obtain high beta-glucosidase yields. The factors in the optimization experiment were the concentrations of cellulose, peptone, and KH(2)PO(4). Their optimal values were 3.2, 3.0, and 0.2 g/100 ml, respectively. Enzyme assays revealed very high beta-glucosidase (22.2 U/ml) and cellobiase (68.9 U/ml) yields. The avicelase yield was low as compared with that from Trichoderma reesei. Mixtures of S. commune and T. reesei culture filtrates caused faster and more extensive saccharification of Avicel than could be achieved by either filtrate alone. A beta-glucosidase was isolated and purified from the optimized culture filtrate of S. commune. The electrophoretic mobility of the purified beta-glucosidase indicated a molecular weight of 97,000. The amino acid composition was similar to that of beta-glucosidase from T. reesei. The acidic (aspartate and glutamate) residues or their amides or both made up approximately 20% of the protein. The NH(2)-terminal amino acid of the enzyme was histidine.

Effect and Modeling of Glucose Inhibition and In Situ Glucose Removal During Enzymatic Hydrolysis of Pretreated Wheat Straw

Abstract: The enzymatic hydrolysis of lignocellulosic biomass is known to be product-inhibited by glucose. In this study, the effects on cellulolytic glucose yields of glucose inhibition and in situ glucose removal were examined and modeled during extended treatment of heat-pretreated wheat straw with the cellulolytic enzyme system, Celluclast® 1.5 L, from Trichoderma reesei, supplemented with a β-glucosidase, Novozym® 188, from Aspergillus niger. Addition of glucose (0–40 g/L) significantly decreased the enzyme-catalyzed glucose formation rates and final glucose yields, in a dose-dependent manner, during 96 h of reaction. When glucose was removed by dialysis during the enzymatic hydrolysis, the cellulose conversion rates and glucose yields increased. In fact, with dialytic in situ glucose removal, the rate of enzyme-catalyzed glucose release during 48–72 h of reaction recovered from 20–40% to become ≈70% of the rate recorded during 6–24 h of reaction. Although Michaelis–Menten kinetics do not suffice to model the kinetics of the complex multi-enzymatic degradation of cellulose, the data for the glucose inhibition were surprisingly well described by simple Michaelis–Menten inhibition models without great significance of the inhibition mechanism. Moreover, the experimental in situ removal of glucose could be simulated by a Michaelis–Menten inhibition model. The data provide an important base for design of novel reactors and operating regimes which include continuous product removal during enzymatic hydrolysis of lignocellulose.

The active site of Trichoderma reesei cellobiohydrolase II: the role of tyrosine 169

Abstract: Trichoderma reesei cellobiohydrolase II (CBHII) is an exoglucanase cleaving primarily cellobiose units from the non-reducing end of cellulose chains. The beta-1,4 glycosidic bond is cleaved by acid catalysis with an aspartic acid, D221, as the likely proton donor, and another aspartate, D175, probably ensuring its protonation and stabilizing charged reaction intermediates. The catalytic base has not yet been identified experimentally. The refined crystal structure of CBHII also shows a tyrosine residue, Y169, located close enough to the scissile bond to be involved in catalysis. The role of this residue has been studied by introducing a mutation Y169F, and analysing the kinetic and binding behavior of the mutated CBHII. The crystal structure of the mutated enzyme was determined to 2.0 A resolution showing no changes when compared with the structure of native CBHII. However, the association constants of the mutant enzyme for cellobiose and cellotriose are increased threefold and for 4-methylumbelliferyl cellobioside over 50-fold. The catalytic constants towards cellotriose and cellotetraose are four times lower for the mutant. These data suggest that Y169, on interacting with a glucose ring entering the second subsite in a narrow tunnel, helps to distort the glucose ring into a more reactive conformation. In addition, a change in the pH activity profile was observed. This indicates that Y169 may have a second role in the catalysis, namely to affect the protonation state of the active site carboxylates, D175 and D221.