Conservation of Xylose Fermentability in Phlebia Species and Direct Fermentation of Xylan by Selected Fungi.

In efforts to lower the cost of total conversion of lignocellulosic materials, utilization of hemicellulose must be considered. White-rot fungus Phlebia sp. MG-60 can produce ethanol directly from cellulose and has fermentation ability for glucose, cellulose, and xylose. Therefore, white-rot fungi can be considered a good candidate for consolidated bioprocessing to give bioethanol from lignocellulosic biomass, although little information is available on the direct fermentation of xylan. In the present study, some Phlebia species were selected as candidates because of their ability to ferment xylose to ethanol more efficiently than Phlebia sp. MG-60. This process indicated that the basidiomycetes that can produce ethanol from xylose are closely related genetically within the Phlebia genus. The selected Phlebia species showed higher ethanol productivity from corn core and beechwood xylans than Phlebia sp. MG-60. The ethanol yields from corn core xylan in culture with Phlebia acerina HHB11146, Phlebia ludoviciana HHB9640, and Phlebia subochracea HHB8494 were 46.2%, 46.7%, and 39.7% of theoretical maximum, and those from beechwood xylan were 19.09%, 17.7%, and 21.4% of the theoretical maximum, respectively.