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.

Comparison of a fungal (family I) and bacterial (family II) cellulose-binding domain.

Abstract: A family II cellulose-binding domain (CBD) of an exoglucanase/xylanase (Cex) from the bacterium Cellulomonas fimi was replaced with the family I CBD of cellobiohydrolase I (CbhI) from the fungus Trichoderma reesei. Expression of the hybrid gene in Escherichia coli yielded up to 50 mg of the hybrid protein, CexCBDCbhI, per liter of culture supernatant. The hybrid was purified to homogeneity by affinity chromatography on cellulose. The relative association constants (Kr) for the binding of Cex, CexCBDCbhI, the catalytic domain of Cex (p33), and CbhI to bacterial microcrystalline cellulose (BMCC) were 14.9, 7.8, 0.8, and 10.6 liters g-1, respectively. Cex and CexCBDCbhI had similar substrate specificities and similar activities on crystalline and amorphous cellulose. Both released predominantly cellobiose and cellotriose from amorphous cellulose. CexCBDCbhI was two to three times less active than Cex on BMCC, but significantly more active than Cex on soluble cellulose and on xylan. Unlike Cex, the hybrid protein neither bound to alpha-chitin nor released small particles from dewaxed cotton fibers.

Acetyl xylan esterase from trichoderma reesei contains an active-site serine residue and a cellulose-binding domain

Abstract: The axe 1 gene encoding acetyl xylan esterase was isolated from an expression library of the filamentous fungus Trichoderma reesei using antibodies raised against the purified enzyme. Apparently axe 1 codes for the two forms, pI 7 and pI 6.8, of acetyl xylan esterase previously characterized. The axe 1 encodes 302 amino acids including a signal sequence and a putative propeptide. The catalytic domain has no amino acid similarity with the reported acetyl xylan esterases but has a clear similarity, especially in the active site, with fungal cutinases which are serine esterases. Similarly to serine esterases, the axe 1 product was inactivated with phenylmethylsulfonyl fluoride. At its C-terminus it carries a cellulose binding domain of fungal type, which is separated from the catalytic domain by a region rich in serine, glycine, threonine and proline. The binding domain can be separated from the catalytic domain by limited proteolysis without affecting the activity of the enzyme towards acetylated xylan, but abolishing its capability to bind cellulose.

Predominance of Trichoderma and Penicillium in cellulolytic aerobic filamentous fungi from subtropical and tropical forests in China, and their use in finding highly efficient β-glucosidase

Abstract: Cellulose is the most abundant biomass on earth. The major players in cellulose degradation in nature are cellulases produced by microorganisms. Aerobic filamentous fungi are the main sources of commercial cellulase. Trichoderma reesei has been explored extensively for cellulase production; however, its major limitations are its low β-glucosidase activity and inefficiency in biomass degradation. The aim of this work was to isolate new fungal strains from subtropical and tropical forests in China, which produce high levels of cellulase in order to facilitate development of improved commercial cellulases. We isolated 305 fungal strains from 330 samples collected from subtropical and tropical virgin forests in China. Of these, 31 strains were found to have Avicelase activity of more than 0.2 U/ml in liquid batch cultivation. Molecular analyses of the 31 strains based on internal transcribed spacer sequences revealed that 18 were Trichoderma and 13 were Penicillium species. The best-performing isolate was Trichoderma koningiopsis FCD3-1, which had similar Avicelase activity to T. reesei Rut-C30. Most interestingly, strain FCD3-1 exhibited extracellular β-glucosidase activity of 1.18 U/ml, which was approximately 17 times higher than that of Rut-C30. One β-glucosidase secreted by FCD3-1 was purified, and its gene was cloned and identified. The β-glucosidase belonged to glycosyl hydrolase (GH) family 3, sharing the highest identity of 94% with a GH family 3 protein from Trichoderma atroviride IMI 206040, and was designated TkBgl3A. The optimal pH and temperature of TkBgl3A were 4.5 and 65°C, respectively. The enzyme retained over 90% activity for 360 hours at pH 4.0 and 30°C, which are the usual conditions used for simultaneous saccharification and fermentation (SSF) of cellulose to ethanol. The enzyme showed significantly higher specific activity toward natural substrate cellobiose (141.4 U/mg) than toward artificial substrate p-nitrophenyl-beta-D-glucopyranoside (108.0 U/mg). Strains of Trichoderma and Penicillium were the predominant cellulolytic fungi in subtropical and tropical forests in China. T. koningiopsis FCD3-1 was the most efficient producer of cellulase, and also produced a high level of β-glucosidase. The high specific activity toward cellobiose and stability under SSF conditions of the purified β-glucosidase from FCD3-1 indicates its potential application in SSF of cellulose to bioethanol.

The cellulase proteins of Trichoderma reesei: Structure, multiplicity, mode of action and regulation of formation

Abstract: The filamentous fungus Trichoderma reesei is the predominant industrial producer of cellulolytic enzymes by secreting an enzyme system capable of degrading crystalline cellulose, which consists of several cellobiohydrolases, endoglucanases and β-glucosidases. All of these enzymes occur in multiple forms. A critical appraisal of the methods used to assess cellulase multiplicity is presented. By the aid of gene technology, advanced protein analytics and immunology, “true” isoenzymes and proteolytic fragments of all of these enzymes could be identified, and their structure and properties are described. Also, the recent elucidation of the three-dimensional domain structure of cellulases, their active center, and the role of both in the hydrolysis of cellulose are dealt with. Particular emphasis is presented on the differences in the enzymatic reaction mechanisms of cellobiohydrolase I and II, and their synergism.