Comparative analysis of the Trichoderma reesei transcriptome during growth on the cellulase inducing substrates wheat straw and lactose
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ABSTRACT:
ORGANISM(S): Trichoderma reesei QM9414 Trichoderma reesei
PROVIDER: GSE46155 | GEO | 2013/09/17
SECONDARY ACCESSION(S): PRJNA197382
REPOSITORIES: GEO
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Project description:We have examined and compared the transcriptome of T. reesei growing on wheat straw and lactose as carbon sources under otherwise similar conditions. Gene expression on wheat straw exceeded that on lactose, and 1619 genes were found to be only induced on wheat straw but not on lactose. They comprised 30 % of the CAZome, but were also enriched in genes associated with phospholipid metabolism, DNA synthesis and repair and iron homeostatis. Two thirds of the CAZome was expressed both on wheat straw as well as on lactose, but 60 % of it at least >2-fold higher on the former. Major wheat straw specific genes comprised xylanases, chitinases and M-CM-^_-mannosidases. Interestingly, the latter two CAZyme families were significantly higher expressed in a strain in which xyr1 encoding the major regulator of cellulase and hemicellulase biosynthesis is non-functional, demonstrating that XYR1 is a repressor of these genes. We used two biological replicas of four T. reesei strains growing on glucose, lactose, and on wheat straw
2013-09-17 | E-GEOD-46155 | biostudies-arrayexpress
Project description:Trichoderma reesei is known for its ability to produce large amounts of extracellular proteins and is one of the most important industrially used filamentous fungus. Xylanase regulator 1 (XYR1) as the master regulator is responsible for the activation of cellulase and hemicellulase gene expression, normally under inducing conditions. It has been reported that strains with point mutations in certain areas of xyr1 bypass the carbon catabolite repression, allowing cellulase and hemicellulase production even in the presence of glucose. These mutations also change the profile of produced proteins, shifting it more towards xylanase production, and increase the overall protein production in inducing conditions. However, how these mutations alter the metabolism and other cellular processes to cause these changes remains unclear. In the present study, our aim was to explore changes caused by a point mutation in xyr1 on transcriptomic and metabolic level to better understand the reasons behind the increased protein production in both repressing glucose and inducing lactose conditions. We observed that the xyr1 mutant strain built more biomass and produced more extracellular proteins during growth on lactose compared to the wild type xyr1 strain. Genes involved in oxidoreductive D-galactose catabolism pathway were upregulated in the xyr1 mutant strain, potentially contributing to the more efficient utilization of lactose. The shift from utilizing lactose to using glucose as carbon source seemed faster in the xyr1 mutant strain. Clustering and enrichment analysis showed over-representation of mitochondria-related Gene Ontology terms in clusters where gene expression was higher in the xyr1 mutant, indicating that mitochondria play a role in the altered metabolic state associated with the xyr1 mutation. Metabolomics revealed that free tyrosine was more abundant in the xyr1 mutant strain in all measured timepoints, whereas multiple fatty acids were less abundant in the mutant strain on glucose. The results contribute to more in-depth knowledge on T. reesei physiology and aid in finding new targets for improved protein production.
2024-07-19 | GSE260567 | GEO
Project description:Background: Saprobic fungi are the predominant industrial sources of Carbohydrate Active enZymes (CAZymes) used for the saccharification of lignocellulose during the production of second generation biofuels. The production of more effective enzyme cocktails is a key objective for efficient biofuel production. To achieve this objective, it is crucial to understand the response of fungi to lignocellulose substrates. Our previous study used RNA-seq to identify the genes induced in Aspergillus niger in response to wheat straw, a biofuel feedstock, and showed that the range of genes induced was greater than previously seen with simple inducers [GSE33852]. Results: In this work we used RNA-seq to identify the genes induced in A. niger in response to short rotation coppice willow and compared this with the response to wheat straw from our previous study, at the same time-point. The response to willow showed a large increase in expression of genes encoding CAZymes. Genes encoding the major activities required to saccharify lignocellulose were induced on willow such as endoglucanases, cellobiohydrolases and xylanases. The transcriptome response to willow had many similarities with the response to straw with some significant differences in the expression levels of individual genes which are discussed in relation to differences in substrate composition or other factors. Differences in transcript levels include higher levels on wheat straw from genes encoding enzymes classified as members of GH62 (an arabinofuranosidase) and CE1 (a feruloyl esterase) CAZy families whereas two genes encoding endoglucanases classified as members of the GH5 family had higher transcript levels when exposed to willow. There were changes in the cocktail of enzymes secreted by A. niger when cultured with willow or straw. Assays for particular enzymes as well as saccharification assays were used to compare the enzyme activities of the cocktails. Wheat straw induced an enzyme cocktail that saccharified wheat straw to a greater extent than willow. Genes not encoding CAZymes were also induced on willow such as hydrophobins as well as genes of unknown function. Several genes were identified as promising targets for future study. Conclusions: By comparing this first study of the global transcriptional response of a fungus to willow with the response to straw, we have shown that the inducing lignocellulosic substrate has a marked effect upon the range of transcripts and enzymes expressed by A. niger. The use by industry of complex substrates such as wheat straw or willow could benefit efficient biofuel production.
2015-04-13 | GSE62284 | GEO
Project description:Background: Saprobic fungi are the predominant industrial sources of Carbohydrate Active enZymes (CAZymes) used for the saccharification of lignocellulose during the production of second generation biofuels. The production of more effective enzyme cocktails is a key objective for efficient biofuel production. To achieve this objective, it is crucial to understand the response of fungi to lignocellulose substrates. Our previous study used RNA-seq to identify the genes induced in Aspergillus niger in response to wheat straw, a biofuel feedstock, and showed that the range of genes induced was greater than previously seen with simple inducers [GSE33852]. Results: In this work we used RNA-seq to identify the genes induced in A. niger in response to short rotation coppice willow and compared this with the response to wheat straw from our previous study, at the same time-point. The response to willow showed a large increase in expression of genes encoding CAZymes. Genes encoding the major activities required to saccharify lignocellulose were induced on willow such as endoglucanases, cellobiohydrolases and xylanases. The transcriptome response to willow had many similarities with the response to straw with some significant differences in the expression levels of individual genes which are discussed in relation to differences in substrate composition or other factors. Differences in transcript levels include higher levels on wheat straw from genes encoding enzymes classified as members of GH62 (an arabinofuranosidase) and CE1 (a feruloyl esterase) CAZy families whereas two genes encoding endoglucanases classified as members of the GH5 family had higher transcript levels when exposed to willow. There were changes in the cocktail of enzymes secreted by A. niger when cultured with willow or straw. Assays for particular enzymes as well as saccharification assays were used to compare the enzyme activities of the cocktails. Wheat straw induced an enzyme cocktail that saccharified wheat straw to a greater extent than willow. Genes not encoding CAZymes were also induced on willow such as hydrophobins as well as genes of unknown function. Several genes were identified as promising targets for future study. Conclusions: By comparing this first study of the global transcriptional response of a fungus to willow with the response to straw, we have shown that the inducing lignocellulosic substrate has a marked effect upon the range of transcripts and enzymes expressed by A. niger. The use by industry of complex substrates such as wheat straw or willow could benefit efficient biofuel production. Six samples in total consisting of duplicate shake flask Aspergillus niger cultures from three conditions: glucose 48 h, willow 24 h, willow 24 h + glucose 5 h
2015-04-13 | E-GEOD-62284 | biostudies-arrayexpress
Project description:Understanding the coordinated regulation of the hundreds of carbohydrate-active enzyme (CAZyme) genes occurring in the genomes of fungi has great practical importance. We recorded genome-wide transcriptional changes of Aspergillus nidulans cultivated on glucose, lactose or arabinogalactan as well as under carbon starved conditions. We determined both carbon stress specific changes (a carbon stress vs. glucose) and culture specific changes (a culture vs. all other cultures). Many CAZyme genes showed carbon stress specific and/or culture specific upregulation on arabinogalactan (138 and 62 genes, respectively). Besides galactosidase and arabinan degrading enzyme genes, enrichment of cellulolytic, pectinolytic, mannan and xylan degrading enzyme genes were observed in these gene sets. Less, 81 and 107 carbon stress specific as well as 6 and 16 culture specific upregulated genes were found on lactose and in carbon starved cultures, respectively. They were enriched only in galactosidase and xylosidase genes on lactose and rhamnogalacturonanase genes in both cultures. Some CAZyme genes (29 genes) showed culture specific upregulation on glucose and they were enriched in beta-1,4-glucanase genes. Behavioral ecological background of these characteristics was evaluated to organize comprehensively our knowledge on CAZyme production, which can lead to develop new strategies to produce enzymes for plant cell wall saccharification.
2022-01-26 | GSE189016 | GEO
Project description:The regulation of plant biomass degradation by fungi is critical to the carbon cycle, and applications in bioproducts and biocontrol. Trichoderma harzianum is an important plant biomass degrader, enzyme producer, and biocontrol agent, but few putative major transcriptional regulators have been deleted in this species. The T. harzianum ortholog of the transcriptional activator XYR1/XlnR/XLR-1 was deleted, and the mutant strains were analyzed by growth profiling, enzymatic activities, and transcriptomics on cellulose. From plate cultures, the Δxyr1 mutant had reduced growth on D-xylose, xylan, and cellulose, and from shake-flask cultures with cellulose, the Δxyr1 mutant had ~ 90% lower β-glucosidase activity, and no detectable β-xylosidase or cellulase activity. The comparison of the transcriptomes from 18 h shake-flask cultures on D-fructose, without a carbon source, and cellulose, showed major effects of XYR1 deletion whereby the Δxyr1 mutant on cellulose was transcriptionally most similar to the cultures without a carbon source. The cellulose induced 43 plant biomass-degrading CAZymes including xylanases as well as cellulases, and most of these had massively lower expression in the Δxyr1 mutant. Expression of a sub-set of carbon catabolic enzymes, other transcription factors, and sugar transporters was also lower in the Δxyr1 mutant on cellulose. In summary, T. harzianum XYR1 is the master regulator of cellulases and xylanases, as well as regulating carbon catabolic enzymes.
2023-12-26 | GSE252008 | GEO
Project description:Fungi are an important source of enzymes for saccharification of plant polysaccharides and production of biofuels. Understanding of the regulation and induction of expression of genes encoding these enzymes is still incomplete. To explore the induction mechanism, we analysed the response of the industrially important fungus Aspergillus niger to wheat straw, with a focus on events occurring shortly after exposure to the substrate. RNA sequencing showed that over a third of the genes induced after 6 h of exposure to wheat straw were also induced during 6 h of carbon starvation, indicating that carbon starvation is probably an important factor in the early response to wheat straw. The up-regulation of the expression of a high number of genes encoding CAZymes that are active on plant-derived carbohydrates during early carbon starvation suggests that these enzymes could be involved in a scouting role during starvation, releasing inducing sugars from complex plant polysaccharides. Eight samples in total consisting of duplicate shake flask Aspergillus niger cultures from four conditions: 48h glucose, 6 h starvation, 6 h wheat straw, 24 h starvation
2014-08-22 | E-GEOD-57315 | biostudies-arrayexpress
Project description:The induction of genes in response to exposure of T. reesei to wheat straw was explored using genome-wide RNA-seq and compared to published RNA-seq data and model of how A. niger senses and responds to the lignocellulose. After 24 h of exposure to straw, transcript levels of known and predicted lignocellulose-degrading enzymes increased to around 8% of total cellular mRNA in T. reesei, which was much less when compared to A. niger. The bulk of enzymes used to deconstruct wheat straw is similar in both fungi. Other, non-plant cell wall-degrading enzymes which may aid in lignocellulose degradation were also uncovered in T. reesei and similar to those described in A. niger. Antisense transcripts were also shown to be present in T. reesei and their expession can be regulated by the respective growth condition. Triplicate samples of T. reesei cultivated in each of the three following conditions were taken: 1) After 48 h growth in glucose-based minimal media; 2) After transfer of mycelia from glucose-based media into media containing wheat straw as a sole carbon source and 3) 5 h after addition of glucose to straw cultures.
2013-04-01 | E-GEOD-44648 | biostudies-arrayexpress
Project description:Fungi are an important source of enzymes for saccharification of plant polysaccharides and production of biofuels. Understanding of the regulation and induction of expression of genes encoding these enzymes is still incomplete. To explore the induction mechanism, we analysed the response of the industrially important fungus Aspergillus niger to wheat straw, with a focus on events occurring shortly after exposure to the substrate. RNA sequencing showed that over a third of the genes induced after 6 h of exposure to wheat straw were also induced during 6 h of carbon starvation, indicating that carbon starvation is probably an important factor in the early response to wheat straw. The up-regulation of the expression of a high number of genes encoding CAZymes that are active on plant-derived carbohydrates during early carbon starvation suggests that these enzymes could be involved in a scouting role during starvation, releasing inducing sugars from complex plant polysaccharides.
2014-08-22 | GSE57315 | GEO
Project description:Wheat straw grown cultures of T. reesei QM9414 were supplemented with 100 µM L-methionine and the genome wide gene expression monitored in order to find novel L-Methionine repressible genes. Total RNA was isolated from independent duplicate shake flask cultures of T. reesei QM9414 pregrown on pretreated wheat straw. Global gene and analyzed using a 4 chip design where 2 chips each represented cultures with or without exogeneously added 100 µM L- Methionine.
2015-06-11 | E-GEOD-69745 | biostudies-arrayexpress