Genomic and transcriptomic analysis of the thermophilic lignocellulose-degrading fungus Thielavia terrestris LPH172

Abstract

Background: Biomass-degrading enzymes with improved activity and stability can ameliorate substrate saccharification and make biorefineries economically feasible. Filamentous fungi are a rich source of carbohydrate-active enzymes (CAZymes) for biomass degradation. The newly isolated LPH172 strain of the thermophilic Ascomycete Thielavia terrestris has been shown to possess high xylanase and cellulase activities and tolerate well low pH and high temperatures. Here, we aimed to illuminate the lignocellulose degrading machinery and novel carbohydrate-active enzymes in LPH172 in detail.Results: We sequenced and analysed the 36.6-Mb genome and transcriptome of LPH172 during growth on glucose, cellulose, rice straw, and beechwood xylan. In total, 411 CAZy domains were found among 10,128 predicted genes. Compared to other fungi, auxiliary activity (AA) enzymes were particularly enriched. GC content was higher in coding sequences than in the overall genome. A high GC3 content was hypothesised to contribute to thermophilicity. T. terrestris employed mainly lytic polysaccharide monooxygenases (LPMOs) and glycoside hydrolase (GH) family 7 glucanases to attack cellulosic substrates, and conventional hemicellulases (GH10 and GH11) to degrade xylan. The observed co-expression and co-upregulation of AA9 LPMOs, other AA CAZymes, and (hemi)cellulases points to a complex and nuanced degradation strategy. Growth on more complex and heterogeneous substrates resulted in a more varied but generally lower gene expression. Conclusions: Our analysis of the genome and transcriptome of T. terrestris LPH172 elucidates the enzyme arsenal the fungus uses to degrade lignocellulosic substrates. The study provides the basis for future characterisation of potential new enzymes for industrial biomass saccharification.

Network Analysis Reveals Different Cellulose Degradation Strategies acrossTrichoderma harzianumStrains Associated with XYR1 and CRE1

“…Our findings suggest that the set of transcripts related to XYR1 and CRE1 varies among the studied T. harzianum strains, suggesting regulatory differences in enzymatic hydrolysis. These findings corroborate previous studies in which differences in biomass degradation and enzyme production between strains of the same species have been reported (de Vries, et al 2017;Thanh, et al 2019;Tolgo, et al 2021). Furthermore, such XYR1 and CRE1 Response to Cellulose Degradation transcripts were not limited to CAZymes and other proteins related to biomass degradation.…”

Phylogenetic analysis and in-depth characterization of functionally and structurally diverse CE5 cutinases

“…Secondly, the biodiversity should be spanned, using both enzymes from the well analyzed clades (Figure S4, clades A, B, and C; SI-1) as well as from under-investigated areas of the tree (Figure 1). Thirdly, from our previous transcriptome studies of Malbranchea cinnamomea and Thielavia terrestris (26,27), we have identified two cutinases significantly overexpressed on lignocellulolytic substrates, which were also added to the list. Finally, we added a cutinase from Sirococcus conginenus because of its suggested acid tolerance (19), a trait important in a biorefinery context where pretreatment results in low pH of the biomass slurries (25).…”