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.

Characterization of the cellulolytic activity of a Bacillus isolate.

Abstract: A group I Bacillus strain, DLG, was isolated and characterized as being most closely related to Bacillus subtilis. When grown on any of a variety of sugars, the culture supernatant of this isolate was found to possess cellulolytic activity, as demonstrated by degradation of trinitrophenyl-carboxymethyl cellulose. Growth in medium containing cellobiose or glucose resulted in the greatest production of cellulolytic activity. The cellulolytic activity was not produced until the stationary phase of growth, and the addition of glucose or cellobiose to a culture in this phase had no apparent effect on enzyme production. Fractionation of the culture supernatant showed that the molecular weight of the enzymatic activity was less than 100,000. Maximum cellulolytic activity in assays was observed at pH 4.8 and at 58C, although maximum thermal stability of the activity. Kinetic experiments suggested that more than one enzyme was acting upon trinitrophenyl-carboxymethyl cellulose. Exocellular protein produced by this Bacillus isolate showed roughly one-fifth the cellulolytic activity displayed by Trichoderma reesei C30 on noncrystalline, cellulosic substrates. In contrast to T. reesei cellulase, the Bacillus enzymatic activity showed no ability to degrade crystalline forms of cellulose, nor was cellobiase activity detectable.

Functional analysis of the cellobiohydrolase I promoter of the filamentous fungus Trichoderma reesei

Abstract: Functional analysis of the cellulase promoter cbh1 of the filamentous fungus Trichoderma reesei was carried out using the Escherichia coli lacZ gene as a reporter. An assay based on cultivation on solid medium in microtiter plates was developed that allows rapid and reliable semiquantitative analysis of β-galactosidase expression of a large number of transformants. A series of deletions and specifically designed alterations were made covering 2.2 kb of the cbh1 promoter. Removal of sequences upstream of nucleotide −500 in relation to the initiator ATG abolished glucose repression. Mutation of a single hexanucleotide sequence 5′GTGGGG at nucleotide −720 was sufficient for derepression. This site is similar to the binding sites of the glucose repressors MIG1 of Saccharomyces cerevisiae and CREA/CREI of filamentous fungi. Removal of the glucose repressor site did not affect sophorose induction. Sophorose induction of the promoter was retained even in deletion derivatives lacking sequences upstream of position −161, which retained about 70 bp upstream of the transcription start point and only 30 bp upstream of the TATA box.

An acetyl esterase of Trichoderma reesei and its role in the hydrolysis of acetyl xylans

Abstract: An acetyl esterase was purified from Trichoderma reesei by cation and anion exchange chromatography. The enzyme had a molecular weight of 45 000 as determined by SDS-electrophoresis, or 67 000 as determined by gel filtration. In chromatofocusing the enzyme was shown to consist of two isoenzymes with isoelectric points of 6.8 and 6.0. The enzyme showed activity towards naphthyl acetate, triacetin and glucose-and xylose acetates. However, it liberated acetic acid from acetylated xylo-oligomers only to a small extent. The liberation of acetic acid from the oligomeric substrate was enhanced by addition of endoxylanase and β-xylosidase.

Lignin triggers irreversible cellulase loss during pretreated lignocellulosic biomass saccharification

Abstract: Non-productive binding of enzymes to lignin is thought to impede the saccharification efficiency of pretreated lignocellulosic biomass to fermentable sugars. Due to a lack of suitable analytical techniques that track binding of individual enzymes within complex protein mixtures and the difficulty in distinguishing the contribution of productive (binding to specific glycans) versus non-productive (binding to lignin) binding of cellulases to lignocellulose, there is currently a poor understanding of individual enzyme adsorption to lignin during the time course of pretreated biomass saccharification. In this study, we have utilized an FPLC (fast protein liquid chromatography)-based methodology to quantify free Trichoderma reesei cellulases (namely CBH I, CBH II, and EG I) concentration within a complex hydrolyzate mixture during the varying time course of biomass saccharification. Three pretreated corn stover (CS) samples were included in this study: Ammonia Fiber Expansiona (AFEX™-CS), dilute acid (DA-CS), and ionic liquid (IL-CS) pretreatments. The relative fraction of bound individual cellulases varied depending not only on the pretreated biomass type (and lignin abundance) but also on the type of cellulase. Acid pretreated biomass had the highest levels of non-recoverable cellulases, while ionic liquid pretreated biomass had the highest overall cellulase recovery. CBH II has the lowest thermal stability among the three T. reesei cellulases tested. By preparing recombinant family 1 carbohydrate binding module (CBM) fusion proteins, we have shown that family 1 CBMs are highly implicated in the non-productive binding of full-length T. reesei cellulases to lignin. Our findings aid in further understanding the complex mechanisms of non-productive binding of cellulases to pretreated lignocellulosic biomass. Developing optimized pretreatment processes with reduced or modified lignin content to minimize non-productive enzyme binding or engineering pretreatment-specific, low-lignin binding cellulases will improve enzyme specific activity, facilitate enzyme recycling, and thereby permit production of cheaper biofuels.