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Accumulation of sugar from pulp and xylitol from xylose by pyruvate decarboxylase-negative white-rot fungus Phlebia sp. MG-60

Tsuyama, Taku, Yamaguchi, Megumi, Kamei, Ichiro
Bioresource technology 2017 v.238 pp. 241-247
Phlebia, biochemical pathways, biomass, ethanol, fermentation, glucose, hardwood, homologous recombination, kraft pulp, lignocellulose, metabolic engineering, phenotype, protoplasts, pyruvate decarboxylase, white-rot fungi, xylitol, xylose
Phlebia sp. MG-60 is a white-rot fungus that produces ethanol with high efficiency from lignocellulosic biomass without additional enzymes. Through engineering of this powerful metabolic pathway for fermentation in Phlebia sp. MG-60, chemical compounds other than ethanol could be produced. Here, we demonstrate sugar accumulation from unbleached hardwood kraft pulp and conversion of xylose to xylitol by pyruvate decarboxylase (pdc)-negative Phlebia sp. MG-60. We isolated Phlebia sp. strain MG-60-P2 from protoplasts to unify the protoplast phenotypes of the regenerated strains. Homologous recombination achieved a stable pdc-knockout line, designated KO77. The KO77 line produced traces of ethanol, but accumulated xylitol from xylose or glucose from unbleached hardwood kraft pulp. These metabolic changes in the pdc-knockout strain reflect the potential of metabolic engineering in Phlebia sp. MG-60 for direct production of chemical compounds from lignocellulosic biomass.