Project description:A 1,4-beta-D-glucan cellobiohydrolase (EC 3.2.1.91) was purified from the culture liquid of Trichoderma reesei by using biospecific sorption on amorphous cellulose and immunoaffinity chromatography. A single protein band in polyacrylamide-gel electrophoresis and one arc in immunoelectrophoresis corresponded to the enzyme activity. The Mr was 65 000. The pI was 4.2-3.6. The purified enzyme contained about 10% hexose. The enzyme differs from previously described cellobiohydrolases in being more effective in the hydrolysis of cellulose.
Project description:BackgroundThe tropical ascomycete Trichoderma reesei (Hypocrea jecorina) represents one of the most efficient plant cell wall degraders. Regulation of the enzymes required for this process is affected by nutritional signals as well as other environmental signals including light.ResultsOur transcriptome analysis of strains lacking the photoreceptors BLR1 and BLR2 as well as ENV1 revealed a considerable increase in the number of genes showing significantly different transcript levels in light and darkness compared to wild-type. We show that members of all glycoside hydrolase families can be subject to light dependent regulation, hence confirming nutrient utilization including plant cell wall degradation as a major output pathway of light signalling. In contrast to N. crassa, photoreceptor mediated regulation of carbon metabolism in T. reesei occurs primarily by BLR1 and BLR2 via their positive effect on induction of env1 transcription, rather than by a presumed negative effect of ENV1 on the function of the BLR complex. Nevertheless, genes consistently regulated by photoreceptors in N. crassa and T. reesei are significantly enriched in carbon metabolic functions. Hence, different regulatory mechanisms are operative in these two fungi, while the light dependent regulation of plant cell wall degradation appears to be conserved.Analysis of growth on different carbon sources revealed that the oxidoreductive D-galactose and pentose catabolism is influenced by light and ENV1. Transcriptional regulation of the target enzymes in these pathways is enhanced by light and influenced by ENV1, BLR1 and/or BLR2. Additionally we detected an ENV1-regulated genomic cluster of 9 genes including the D-mannitol dehydrogenase gene lxr1, with two genes of this cluster showing consistent regulation in N. crassa.ConclusionsWe show that one major output pathway of light signalling in Trichoderma reesei is regulation of glycoside hydrolase genes and the degradation of hemicellulose building blocks. Targets of ENV1 and BLR1/BLR2 are for the most part distinct and indicate individual functions for ENV1 and the BLR complex besides their postulated regulatory interrelationship.
Project description:We investigated the function of the transcription factor STE12 and found an involvement in gene expression and growth in light and darkness
Project description:We perform a self hybridisation comprative genomic hybridization (CGH) in order to validate the probe tiling design we done on Trichoderma reesei. This hybridization was done using QM6a wild type strain.
Project description:To investigate the potential role in mycoparasitism, microarrays were used to examine T. reesei transcript levels when confronted with a potential prey (the plant pathogen Rhizoctonia solani) before contact, during first physical contact and during overgrowth of the host.
Project description:Background:In addition to its outstanding cellulase production ability, Trichoderma reesei produces a wide variety of valuable secondary metabolites, the production of which has not received much attention to date. Among them, sorbicillinoids, a large group of hexaketide secondary metabolites derived from polyketides, are drawing a growing interest from researchers because they exhibit a variety of important biological functions, including anticancer, antioxidant, antiviral, and antimicrobial properties. The development of fungi strains with constitutive, hyperproduction of sorbicillinoids is thus desired for future industry application but is not well-studied. Moreover, although T. reesei has been demonstrated to produce sorbicillinoids with the corresponding gene cluster and biosynthesis pathway proposed, the underlying molecular mechanism governing sorbicillinoid biosynthesis remains unknown. Results:Recombinant T. reesei ZC121 was constructed from strain RUT-C30 by the insertion of the gene 12121-knockout cassette at the telomere of T. reesei chromosome IV in consideration of the off-target mutagenesis encountered during the unsuccessful deletion of gene 121121. Strain ZC121, when grown on cellulose, showed a sharp reduction of cellulase production, but yet a remarkable enhancement of sorbicillinoids production as compared to strain RUT-C30. The hyperproduction of sorbicillinoids is a constitutive process, independent of culture conditions such as carbon source, light, pH, and temperature. To the best of our knowledge, strain ZC121 displays record sorbicillinoid production levels when grown on both glucose and cellulose. Sorbicillinol and bisvertinolone are the two major sorbicillinoid compounds produced. ZC121 displayed a different morphology and markedly reduced sporulation compared to RUT-C30 but had a similar growth rate and biomass. Transcriptome analysis showed that most genes involved in cellulase production were downregulated significantly in ZC121 grown on cellulose, whereas remarkably all genes in the sorbicillinoid gene cluster were upregulated on both cellulose and glucose. Conclusion:A constitutive sorbicillinoid-hyperproduction strain T. reesei ZC121 was obtained by off-target mutagenesis, displaying an overwhelming shift from cellulase production to sorbicillinoid production on cellulose, leading to a record for sorbicillinoid production. For the first time, T. reesei degraded cellulose to produce platform chemical compounds other than protein in high yield. We propose that the off-target mutagenesis occurring at the telomere region might cause chromosome remodeling and subsequently alter the cell structure and the global gene expression pattern of strain ZC121, as shown by phenotype profiling and comparative transcriptome analysis of ZC121. Overall, T. reesei ZC121 holds great promise for the industrial production of sorbicillinoids and serves as a good model to explore the regulation mechanism of sorbicillinoids' biosynthesis.
Project description:We overexpressed the err1 gene in the Trichoderma reesei wild-type and in the cellulase hyperproducing, carbon catabolite derepressed strain Rut-C30 in order to investigate the possibility of producing erythritol with T. reesei. Two different promoters were used for err1 overexpression in both strains, a constitutive (the native pyruvat kinase (pki) promoter) and an inducible one (the native ?-xylosidase (bxl1) promoter). The derived recombinant strains were precharacterized by analysis of err1 transcript formation on D-xylose and xylan. Based on this, one strain of each type was chosen for further investigation for erythritol production in shake flasks and in bioreactor experiments. For the latter, we used wheat straw pretreated by an alkaline organosolve process as lignocellulosic substrate. Shake flask experiments on D-xylose showed increased erythritol formation for both, the wild-type and the Rut-C30 overexpression strain compared to their respective parental strain. Bioreactor cultivations on wheat straw did not increase erythritol formation in the wild-type overexpression strain. However, err1 overexpression in Rut-C30 led to a clearly higher erythritol formation on wheat straw.
Project description:The filamentous fungus Trichoderma reesei is used on an industrial scale to produce enzymes of biotechnological interest. This fungus has a complex cellulolytic system involved in the degradation of lignocellulosic biomass. However, several aspects related to the regulation of the expression of holocellulolytic genes and the production of cellulases by this fungus are still understood. Here, we constructed a null mutant strain for the xyloglucanase cel74a gene and performed the characterization of the Δcel74a strain to evaluate the genetic regulation of the holocellulases during sugarcane bagasse (SCB) cultivation. Our results demonstrate that the deletion of xyloglucanase cel74a may impact the regulation of holocellulase expression during SCB cultivation. The expression of cellulases cel7a, cel7b, and cel6a was reduced in Δcel74a strain, while the hemicellulases xyn1 and xyn2 were increased in the presence of SCB. The cel74a mutation also affected the xyloglucan hydrolysis patterns. In addition, CEL74A activity was modulated in the presence of calcium, suggesting that this ion may be required for efficient degradation of xyloglucan. CEL74A affects the regulation of holocellulolytic genes and the efficient degradation of SCB in T. reesei. This data makes a significant contribution to our understanding of the carbon utilization of fungal strains as a whole.
Project description:The ability of Trichoderma reesei, a fungus widely used for the commercial production of hemicellulases and cellulases, to grow and modify technical soda lignin was investigated. By quantifying fungal genomic DNA, T. reesei showed growth and sporulation in solid and liquid cultures containing lignin alone. The analysis of released soluble lignin and residual insoluble lignin was indicative of enzymatic oxidative conversion of phenolic lignin side chains and the modification of lignin structure by cleaving the β-O-4 linkages. The results also showed that polymerization reactions were taking place. A proteomic analysis conducted to investigate secreted proteins at days 3, 7, and 14 of growth revealed the presence of five auxiliary activity (AA) enzymes in the secretome: AA6, AA9, two AA3 enzymes), and the only copper radical oxidase encoded in the genome of T. reesei. This enzyme was heterologously produced and characterized, and its activity on lignin-derived molecules was investigated. Phylogenetic characterization demonstrated that this enzyme belonged to the AA5_1 family, which includes characterized glyoxal oxidases. However, the enzyme displayed overlapping physicochemical and catalytic properties across the AA5 family. The enzyme was remarkably stable at high pH and oxidized both, alcohols and aldehydes with preference to the alcohol group. It was also active on lignin-derived phenolic molecules as well as simple carbohydrates. HPSEC and LC-MS analyses on the reactions of the produced protein on lignin dimers (SS ββ, SS βO4 and GG β5) uncovered the polymerizing activity of this enzyme, which was accordingly named lignin copper oxidase (TrLOx). Polymers of up 10 units were formed by hydroxy group oxidation and radical formation. The activations of lignin molecules by TrLOx along with the co-secretion of this enzyme with reductases and FAD flavoproteins oxidoreductases during growth on lignin suggest a synergistic mechanism for lignin breakdown.
Project description:Filamentous fungi are indispensable biotechnological tools for the production of organic chemicals, enzymes, and antibiotics. Most of the strains used for industrial applications have been--and still are--screened and improved by classical mutagenesis. Sexual crossing approaches would yield considerable advantages for research and industrial strain improvement, but interestingly, industrially applied filamentous fungal species have so far been considered to be largely asexual. This is also true for the ascomycete Trichoderma reesei (anamorph of Hypocrea jecorina), which is used for production of cellulolytic and hemicellulolytic enzymes. In this study, we report that T. reesei QM6a has a MAT1-2 mating type locus, and the identification of its respective mating type counterpart, MAT1-1, in natural isolates of H. jecorina, thus proving that this is a heterothallic species. After being considered asexual since its discovery more than 50 years ago, we were now able to induce sexual reproduction of T. reesei QM6a and obtained fertilized stromata and mature ascospores. This sexual crossing approach therefore opens up perspectives for biotechnologically important fungi. Our findings provide a tool for fast and efficient industrial strain improvement in T. reesei, thus boosting research toward economically feasible biofuel production. In addition, knowledge of MAT-loci and sexual crossing techniques will facilitate research with other Trichoderma spp. relevant for agriculture and human health.