Browsing by Subject "LIGNOCELLULOSE"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Pakarinen, Annukka; Haven, Mai Ostergaard; Djajadi, Demi Tristan; Varnai, Aniko; Puranen, Terhi; Viikari, Liisa (2014)
  • Wallenius, Janne; Kontro, Jussi; Lyra, Christina; Kuuskeri, Jaana; Wan, Xing; Kahkonen, Mika A.; Baig, Irshad; Kamer, Paul C. J.; Sipila, Jussi; Makela, Miia R.; Nousiainen, Paula; Hilden, Kristiina (2021)
    Fungal laccases are attracting enzymes for sustainable valorization of biorefinery lignins. To improve the lignin oxidation capacity of two previously characterized laccase isoenzymes from the white-rot fungus Obba rivulosa, we mutated their substrate-binding site at T1. As a result, the pH optimum of the recombinantly produced laccase variant rOrLcc2-D206N shifted by three units towards neutral pH. O. rivulosa laccase variants with redox mediators oxidized both the dimeric lignin model compound and biorefinery poplar lignin. Significant structural changes, such as selective benzylic alpha-oxidation, were detected by nuclear magnetic resonance analysis, although no polymerization of lignin was observed by gel permeation chromatography. This suggests that especially rOrLcc2-D206N is a promising candidate for lignin-related applications.
  • Lundell, Taina K.; Mäkelä, Miia R.; de Vries, Ronald P.; Hilden, Kristiina S. (Academic Press, 2014)
    Advances in Botanical Research
    Saprobic (saprotrophic and saprophytic) wood-decay fungi are in majority species belonging to the fungal phylum Basidiomycota, whereas saprobic plant litter-decomposing fungi are species of both the Basidiomycota and the second Dikarya phylum Ascomycota. Wood-colonizing white rot and brown rot fungi are principally polypore, gilled pleurotoid, or corticioid Basidiomycota species of the class Agaricomycetes, which also includes forest and grassland soil-inhabiting and litter-decomposing mushroom species. In this chapter, examples of lignocellulose degradation patterns are presented in the current view of genome sequencing and comparative genomics of fungal wood-decay enzymes. Specific attention is given to the model white rot fungus, lignin-degrading species Phanerochaete chrysosporium and its wood decay-related gene expression (transcriptomics) on lignocellulose substrates. Types of fungal decay patterns on wood and plant lignocellulose are discussed in the view of fungal lifestyle strategies. Potentiality of the plant biomass-decomposing Basidiomycota species, their secreted enzymes and respective lignocellulose-attacking genes is evaluated in regard to development of biotechnological and industrial applications.
  • Rytioja, Johanna; Hilden, Kristiina; Di Falco, Marcos; Zhou, Miaomiao; Aguilar-Pontes, Maria Victoria; Sietiö, Outi-Maaria; Tsang, Adrian; de Vries, Ronald; Mäkelä, Miia R. (2017)
    The ability to obtain carbon and energy is a major requirement to exist in any environment. For several ascomycete fungi, (post-)genomic analyses have shown that species that occupy a large variety of habitats possess a diverse enzymatic machinery, while species with a specific habitat have a more focused enzyme repertoire that is well-adapted to the prevailing substrate. White-rot basidiomycete fungi also live in a specific habitat, as they are found exclusively in wood. In this study, we evaluated how well the enzymatic machinery of the white-rot fungus Dichomitus squalens is tailored to degrade its natural wood substrate. The transcriptome and exoproteome of D. squalens were analyzed after cultivation on two natural substrates, aspen and spruce wood, and two non-woody substrates, wheat bran and cotton seed hulls. D. squalens produced ligninolytic enzymes mainly at the early time point of the wood cultures, indicating the need to degrade lignin to get access to wood polysaccharides. Surprisingly, the response of the fungus to the non-woody polysaccharides was nearly as good a match to the substrate composition as observed for the wood polysaccharides. This indicates that D. squalens has preserved its ability to efficiently degrade plant biomass types not present in its natural habitat.