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.

Relationship between the fine structure of native cellulose and cellulose degradability by the cellulase complexes of Trichoderma reesei and Clostridium thermocellum

Abstract: The initial rate of hydrolysis of six commercially available native (type l) celluloses was determined for the crude cellulase complexes of the thermophilic anaerobic bacterium C thermocellum and the mesophilic fungus T reesei These rates were then compared with certain physical features of the substrates in an attempt to determine the role of cellulose structure in its degradability Within the substrate series tested, the Clostridium system showed a greater relative range in rate of enzymatic hydrolysis than did the Trichoderma system Average correlation coefficients for the kinetic rates from bacterial and fungal cellulases, respectively, and the following physical parameters were obtained: relative crystallinity index (RCl) from acid hydrolysis, -061 and -085; RCl from x-ray diffraction, -075 and -089; accessibility to formylation at 4 degrees C, + 049 and +060; nonaccessibility to formylation at 65 degrees C, -040 and -073; fiber saturation point, + 083 and + 085 Kinetic and pore volume distribution data suggest that the rate-limiting components of both the bacterial and fungal cellulase systems are of similar size, approximately 43 A along one axis

Catalytic and substrate-binding domains of endoglucanase 2 from Bacteroides succinogenes.

Abstract: Endoglucanase 2 (EG2) of the cellulolytic ruminal anaerobe Bacteroides succinogenes is a 118-kilodalton (kDa) enzyme which binds to cellulose and produces cellotetraose as the end product of hydrolysis. The purified enzyme was treated with the protease trypsin in an attempt to isolate peptides which retained the ability to either hydrolyze soluble carboxymethyl cellulose or bind to insoluble cellulose. There was no loss in endoglucanase activity (carboxymethylcellulase) over a period of 2 h following the addition of trypsin. In comparison, there was a greater than eightfold reduction in the binding of carboxymethylcellulase activity to crystalline cellulose. A Lineweaver-Burk plot with amorphous cellulose as the substrate revealed that the trypsin-digested enzyme had an identical Vmax but a 1.9-fold-lower Km in comparison with the intact enzyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the trypsin-digested enzyme revealed two major peptides of 43 and 51 kDa (p43 and p51). The 43-kDa peptide was able to bind to both amorphous and crystalline cellulose, whereas p51 did not. Purified p51 had a molar activity toward carboxymethyl cellulose which was identical to that of the intact enzyme, but activity toward both amorphous and crystalline cellulose was reduced approximately twofold. Two high-titer monoclonal antibodies from mice immunized with the intact protein recognized p43 but not p51. The results are consistent with a bifunctional organization of EG2, in which the 118-kDa enzyme is composed of a 51-kDa catalytic domain and a highly antigenic 43-kDa substrate-binding domain. In terms of its domain structure and activity toward cellulose, EG2 is very similar to cellobiohydrolase II of Trichoderma reesei. Images

Microbial exo-xylanases: a mini review.

Abstract: Exo-xylanases are a class of glycosyl hydrolases and play an important role in hydrolysis of xylan to xylose. They belong to glycosyl hydrolase (GH) family 8 with a characteristic (α/α)6 barrel fold in their molecular structures. These enzymes are generally produced by bacteria. Exceptionally, the endo-xylanases from Trichoderma reesei Rut C-30 and a few bacterial strains also show considerable exo-xylanase activities. Exo-xylanases are active on natural xylan substances, hydrolyzing long-chain xylo-oligomers from the reducing end to produce short-chain xylo-oligomers and xylose. Exo-xylanases usually show multiple enzyme functions such as β-xylosidase, exo-glucanase, β-glucosidase, and arabinofuranosidase activities, which are helpful for more efficient hydrolysis of xylan. The combined use of exo- and endo-xylanases can increase the xylose yield compared to using either of them alone. Screening new exo-xylanase-producing microbes, mining the enzyme coding sequences, genetically engineering the enzymes, and producing them in a large scale are recommended for their commercial applications in lignocellulose-based biorefinery.

Substrate-induced production and secretion of cellulases by Clostridium acetobutylicum

Abstract: Clostridium acetobutylicum ATCC 824 is a solventogenic bacterium that grows heterotrophically on a variety of carbohydrates, including glucose, cellobiose, xylose, and lichenan, a linear polymer of beta-1,3- and beta-1,4-linked beta-D-glucose units. C. acetobutylicum does not degrade cellulose, although its genome sequence contains several cellulase-encoding genes and a complete cellulosome cluster of cellulosome genes. In the present study, we demonstrate that a low but significant level of induction of cellulase activity occurs during growth on xylose or lichenan. The celF gene, located in the cellulosome-like gene cluster and coding for a unique cellulase that belongs to glycoside hydrolase family 48, was cloned in Escherichia coli, and antibodies were raised against the overproduced CelF protein. A Western blot analysis suggested a possible catabolite repression by glucose or cellobiose and an up-regulation by lichenan or xylose of the extracellular production of CelF by C. acetobutylicum. Possible reasons for the apparent inability of C. acetobutylicum to degrade cellulose are discussed.