Direct ethanol production from biomass by basidiomycete fungi

Abstract

　Lignocellulosic biomass is an abundant and inexpensive material for bioethanol production that represents a sustainable and renewable fuel, which is environment friendly as it reduces greenhouse gas emissions. Currently, the majority of bioethanol is derived from sugar or starchy crops, an approach that is not sustainable because such processes compete with food sources. As such, the production of bioethanol requires the development of an economically feasible and sustainable process utilizing renewable lignocellulosic materials. However, a bottleneck in the conversion of lignocellulosic materials to biofuels is the costly hydrolysis of the biomass using either enzymatic or acid processes.

In this study, we investigated the ability the white rot fungus Trametes versicolor and the brown rot fungus Neolentinus lepideus to ferment xylose. In addition to efficiently converting xylose to bioethanol, these microorganisms readily converted various hexoses to ethanol, and directly fermented biomass to bioethanol without the requirement of pretreatment with acid or enzyme hydrolysis. The bioethanol yields from the conversion of these lignocellulosic materials were much higher than that previously reported for the fermentation of lignocellulosic biomass by other microorganisms. Consequently, T. versicolor and N. lepideus may permit cost-effective and environment friendly bioethanol production from various starting materials.