What is the strategy for degrading complex lignocellulosic polysaccharides from Trichoderma reeseii? What is the difference between Trichoderma reesei and Aspergillus niger? By using RNA sequencing, the global induction of genes exposed to wheat straw in Richter straw was explored and compared with a model of how black straw perceives and responds to wheat straw.
The burning of fossil fuels comes with many recognized problems affecting the health of the global economy and the environment. Replacing fossil fuels with biofuels will help reduce global carbon monoxide emissions, produce a more favorable greenhouse gas profile, reduce dependence on dwindling petroleum resources, and boost local economic development. Biofuels produced from plant biomass such as grass, wood and lignocellulosic waste, which do not compete with food production, are therefore referred to as second-generation biofuels.
In nature, the degradation of lignocellulosic biomass is catalyzed by enzymes from various microorganisms such as soapy fungi and bacteria, enzymes used for biomass deconstruction and many other industrial applications are often derived from fungi of Trichoderma and Aspergillus species. The overall objective of this study is to investigate strategies for the degradation of complex lignocellulosic polysaccharides by Trichoderma reesei and compare them with the mechanisms used by Aspergillus niger to provide new insights that may lead to the development of new methods for the production of 2G biofuels.
Trichoderma and Aspergillus have many industrial applications due to the production of very high levels of secreted enzymes. This has led to the development of multiple genetic tools in Trypanosoma reesei, including random and targeted mutagenesis to generate cellulase mutants, elucidating regulatory mechanisms regarding monosaccharide metabolic pathways and targeting the secretion system of Trypanosoma reesei in order to produce higher proteins by designing more efficient and thermostable enzymes, to date, it has been found that the genome of Trypanosoma reesei encodes 228 polysaccharide-degrading enzymes representing 61 enzyme families. This is similar to the total number of carbohydrate-degrading enzymes in Aspergillus niger.
This study characterizes the transcriptional changes associated with exposure to wheat straw using next-generation RNA sequencing (RNA-seq) technology with the goal of understanding the steps leading to the deconstruction of this complex lignocellulose substrate. Comparing them with the mechanisms employed by Aspergillus niger described earlier will reveal relevant differences and similarities in lignocellulosic degradation between the two industrially important organisms. The cost of enzymes poses a significant challenge to the cost-effectiveness of biofuel production, and the cost of enzymes can be reduced by a combination of factors.
Firstly, the yield from fungal source enzymes should be maximized, and secondly, the most effective functional combination is required. Other aspects, such as the production site of enzymes, are also important. Ground and autoclaved but untreated wheat straw was used in this study, but various pretreatments were possible when digesting lignocellulose to produce 2G biofuel. This will inevitably alter fungal reactions, and understanding the basis of these reaction mechanisms requires baseline studies using untreated materials.
Experimental studies have shown that transcript levels encoding known and predicted cell wall degradation enzymes are very high (approximately 13% of total mRNA) after 24 h exposure to straw, but lower than recorded levels of Aspergillus niger (approximately 19% of total mRNA). Careful analysis revealed that enzymes from the same family of glycoside hydrolases but different families of carbohydrate esterase and polysaccharide lyase were upregulated in both organisms. In Aspergillus risterii, helper proteins that are hypothesized to play a role in enhancing the carbohydrate structure of Aspergillus niger have also been found, and the induced enzyme class is generally similar to that of Aspergillus niger. Similar to Aspergillus niger, antisense transcripts are present in Aspergillus reesei and their expression is regulated by growth conditions.
Conclusion:
A similar array of enzymes is used to deconstruct solid lignocellulosic substrates to identify Aspergillus niger. This suggests a conservative strategy for lignocellulose degradation in both saponifying fungi. This study provides a basis for further analysis and characterization of highly induced genes in the presence of lignocellulosic substrates. These data will help elucidate the mechanism by which Trypanosoma reesei identifies solid substrates and subsequent degradation, and provide information that can be used to efficiently produce second-generation biofuels.
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