Ethanol production from sugars derived from plant biomass by a novel fungus

Abstract

The concept of transforming renewable plant biomass, and in particular organic waste, to fuels or chemicals continues to attract attention as nonrenewable fossil fuel reserves decrease^1,2. Cellulose and hemicellulose, which comprise more than 70% of plant biomass and are the two most abundant organic compounds in the biosphere, occur in the wastes from agriculture and forestry as well as from vegetable and fruit processing and municipal waste treatment. Recycling of these wastes to useful products helps to prevent pollution. After enzymatic or acid hydrolysis, plant biomass yields mostly cellobiose, xylose and glucose together with mannose, galactose and arabinose. Microorganisms which can ferment such a wide range of sugars, at high concentrations, into a high concentration of ethanol have not been reported previously. Here we report on a novel fungus, Paecilomyces sp. NF1, which is capable of fermenting all of the major sugars derived from hydrolysis of plant biomass to ethanol. In xylose fermentation, the ethanol yield of this fungus remained almost unchanged when the concentration of xylose was increased from 20 to 200 g l⁻¹. The fungus also produced good yields of ethanol from glucose, fructose, cellobiose, arabinose, galactose, mannose and ribose, as well as from the simultaneous saccharification and fermentation (SSF) of cellulose with hemicellulose, and from acid hydrolysates of plant biomass.