Dry biodetoxification of acid pretreated wheat straw for cellulosic ethanol fermentation

Background: The efficient removal of toxic inhibitors from pretreated lignocellulose biomass is crucially important for consequent cellulosic ethanol fermentation. A. resinae ZN1 biodetoxifies all toxic inhibitors at the neutral pH of 4-6, and the neutralization of acid catalyst in the pretreated lignocellulose is required. However, aqueous alkaline solutions such as sodium hydroxide solution and calcium hydroxide slurry are used which generate several difficulties. Results: In this study, a dry biodetoxification method was investigated using dry calcium carbonate (CaCO3) powder as an acid-neutralizing reagent to avoid the use of an aqueous alkaline solution. Dry biodetoxification provides a mild and stable pH without the generation of phenolic compounds. The acid pretreated and dry biodetoxified wheat straw was used as the feedstock of ethanol fermentation and the same performance with the wet biodetoxification using aqueous Ca(OH)(2) slurry. The 72 g/L or 9.1% (v/v) of ethanol produced from wheat straw was very close to that of ethanol from corn starch. Conclusions: Dry biodetoxification provided a practical method to simplify the process of conventional wet biodetoxification to reduce the time, cost and labor.