RESUMO
Trichoderma erinaceum is a filamentous fungus that was isolated from decaying sugarcane straw at a Brazilian ethanol biorefinery. This fungus shows potential as a source of plant cell wall-degrading enzymes (PCWDEs). In this study, we conducted a comprehensive multiomics investigation of T. erinaceum to gain insights into its enzymatic capabilities and genetic makeup. Firstly, we performed genome sequencing and assembly, which resulted in the identification of 10,942 genes in the T. erinaceum genome. We then conducted transcriptomics and secretome analyses to map the gene expression patterns and identify the enzymes produced by T. erinaceum in the presence of different substrates such as glucose, microcrystalline cellulose, pretreated sugarcane straw, and pretreated energy cane bagasse. Our analyses revealed that T. erinaceum highly expresses genes directly related to lignocellulose degradation when grown on pretreated energy cane and sugarcane substrates. Furthermore, our secretome analysis identified 35 carbohydrate-active enzymes, primarily PCWDEs. To further explore the enzymatic capabilities of T. erinaceum, we selected a ß-glucosidase from the secretome data for recombinant production in a fungal strain. The recombinant enzyme demonstrated superior performance in degrading cellobiose and laminaribiose compared to a well-known enzyme derived from Trichoderma reesei. Overall, this comprehensive study provides valuable insights into both the genetic patterns of T. erinaceum and its potential for lignocellulose degradation and enzyme production. The obtained genomic data can serve as an important resource for future genetic engineering efforts aimed at optimizing enzyme production from this fungus.
RESUMO
Cellulases play a key role in enzymatic routes for degradation of plant cell-wall polysaccharides into simple and economically-relevant sugars. However, their low performance on complex substrates and reduced stability under industrial conditions remain the main obstacle for the large-scale production of cellulose-derived products and biofuels. Thus, in this study a novel cellulase with unusual catalytic properties from sugarcane soil metagenome (CelE1) was isolated and characterized. The polypeptide deduced from the celE1 gene encodes a unique glycoside hydrolase domain belonging to GH5 family. The recombinant enzyme was active on both carboxymethyl cellulose and ß-glucan with an endo-acting mode according to capillary electrophoretic analysis of cleavage products. CelE1 showed optimum hydrolytic activity at pH 7.0 and 50 °C with remarkable activity at alkaline conditions that is attractive for industrial applications in which conventional acidic cellulases are not suitable. Moreover, its three-dimensional structure was determined at 1.8 Å resolution that allowed the identification of an insertion of eight residues in the ß8-α8 loop of the catalytic domain of CelE1, which is not conserved in its psychrophilic orthologs. This 8-residue-long segment is a prominent and distinguishing feature of thermotolerant cellulases 5 suggesting that it might be involved with thermal stability. Based on its unconventional characteristics, CelE1 could be potentially employed in biotechnological processes that require thermotolerant and alkaline cellulases.