Polyporales wood-decay fungi for bioconversion of lignocelluloses: genomics, interactions, and decomposition mechanisms studied for bioeconomy and industrial applications

Taina Lundell 1 Mari Mäkinen 1 Hans Mattila 1 Tuulia Mali 1 Firoz Shah 1 Jaana Kuuskeri 1 Pia Laine 2 Olli-Pekka Smolander 2 Lars Paulin 2 Markku Varjosalo 2 Petri Auvinen 2
1Department of Microbiology, University of Helsinki, Helsinki, Finland
2Institute of Biotechnology, University of Helsinki, Helsinki, Finland

Basidiomycota Agaricomycetes, order Polyporales fungi are able to depolymerize wood-lignocellulose components: white-rot species decompose all biopolymers including lignin while brown-rot species are efficient in decomposing wood polysaccharides, mainly cellulose [1]. However, exact details of the degradation processes and the genetic, biochemical and proteomic factors involved are not fully understood despite of accumulating genomic data. Our aim is to combine fungal genomics to functional transcriptomics and proteomics including testing on various lignocellulose substrates for growth and bioconversions, to identify the key genes, proteins and metabolites necessary for decomposition of plant biomasses in ecologically important fungi, also presenting applicability in industrial and environmental biotechnology processes.

Screening of CAZy and oxidoreductase enzyme activities in wood-supplemented cultures demonstrated the proficiency of white-rot Polyporales phlebioid clade species [2], which were further investigated for bioethanol production from recyclable waste lignocelluloses [3]. Genome sequencing of the best, model species Phlebia radiata aided in description of the species’ functional transcriptome and proteome on spruce wood [4], and more recently, transcriptome under fermentative, ethanol producing conditions. Differentially expressed key genes were identified to elucidate the principal metabolic pathways and putative transcription factors operating under fermentative versus respirative conditions, also to promote systems biology and metabolic engineering approaches in near future.

Together with phlebioid species, our concern is to elucidate brown-rot decay of wood conducted by the Polyporales species Fomitopsis pinicola, and its interactions with white-rot fungi [5]. In nature, fungal communities are under dynamic changes, and co-habitation of several species is common upon wood decay. Hyphal contacts and interactomes upon decomposition of lignocelluloses and plant biomasses are challenging to investigate, but may offer us new tools for fungal bioproductions and bioconversions supporting more sustainable bioeconomy.

[1]Lundell (2014) Adv.Bot.Res. 70:329-370

[2]Kuuskeri (2015) BMC Microbiol. 15:217

[3]Mattila (2017) Bioresour.Technol. 225:254-261

[4]Kuuskeri (2016) Biotechnol.Biofuels 9:192

[5]Mali (2017) PLoS ONE 12(9):e0185171