Mixtures of aromatic compounds induce ligninolytic gene expression in the wood-rotting fungus Dichomitus squalens

Abstract

Heterologous production of fungal ligninolytic cocktails is challenging due to the low yields of catalytically active lignin modifying peroxidases. Production using a natural system, such as a wood-rotting fungus, is a promising alternative if specific or preferential induction of the ligninolytic activities could be achieved. Using transcriptomics, gene expression of the white-rot Dichomitus squalens during growth on mixtures of aromatic compounds, with ring structures representing the two major lignin sub-units, was compared to a wood substrate. Most of the genes encoding lignin modifying enzymes (laccases and peroxidases) categorised as highly or moderately expressed on wood were expressed similarly on aromatic compounds. Higher expression levels of a subset of manganese and versatile peroxidases was observed on di-compared to mono-methoxylated aromatics. The expression of polysaccharide degrading enzymes was lower on aromatic compounds compared to wood, demonstrating that the induction of lignin modifying enzymes became more specific. This study suggests potential for aromatic waste streams, e.g. from lignocellulose pretreatment, to produce a lignin-specific enzyme cocktail from D. squalens or other white-rot fungi.

Fungal glycoside hydrolase family 44 xyloglucanases are restricted to the phylum Basidiomycota and show a distinct xyloglucan cleavage pattern

“…In situ expression and production of the D. squalens and P. ostreatus GH44 genes and proteins have been shown in previously published transcriptome and exoproteome datasets ( Daly et al, 2018 ; Wu et al., 2020 , 2021 ). In short, D. squalens CBS464.89 expressed xegA and produced the corresponding protein during growth on spruce and birch wood ( Daly et al, 2018 , 2020 ), whereas P. ostreatus PC9 expressed the XegA encoding gene on rice straw ( Wu et al., 2021 ), and in the Δ pex1 and Δ gat1 mutants on beechwood sawdust ( Wu et al., 2020 ), again supporting a role for these genes in plant biomass degradation. Therefore, these two candidates were selected for further characterization to demonstrate the function of basidiomycete GH44 enzymes.…”

Insights into the cellulose degradation mechanism of the thermophilic fungus Chaetomium thermophilum based on integrated functional omics

“…Plant biomass is recognized as a sustainable source of mixed sugars for fermentation to second generation biofuels and high-value molecules. Fungi have evolved different strategies to degrade lignocellulose [53][54][55][56][57][58]. The genome of the thermophilic fungus C. thermophilum suggested that this fungus should prefer to degrade monocots that are rich in cellulose, xylan and β-glucan.…”

White rot fungi can be a promising tool for removal of bisphenol A, bisphenol S, and nonylphenol from wastewater

“…Each WRF can secrete a distinct type of LME depending on the species or even strain (Torres et al 2003 ; Wesenberg et al 2003 ; Levin et al 2004 ; Yang et al 2013b ; Kinnunen et al 2016 ). The enzymatic pathways of living WRF undergo the control of gene promoters, which are stimulated by an appropriate environmental factor (Suetomi et al 2015 ; Toyokawa et al 2016 ; Daly et al 2020 ). The triggering factor for LMEs is primarily the balance of nitrogen and carbon in the medium.…”