Fermentation of lignocellulosic hydrolysates. I: inhibition and detoxification

The ethanol yield and productivity obtained during fermentation of lignocel lulosic hydrolysates is decreased due to the presence of inhibiting compoun ds, such as weak acids, furans and phenolic compounds formed or released du ring hydrolysis. This review describes the effect of various detoxification methods on the fermentability and chemical composition of the hydrolysates . Inhibition of fermentation can be relieved upon treatment with the lignin olytic enzyme laccase, pre-fermentation by the filamentous fungus Trichoder ma reesei, removal of non-volatile compounds, extraction with ether or ethy l acetate, and treatment with alkali or sulfite. Various fermentation strat egies can also be used to improve yield and productivity in lignocellulosic hydrolysates. Batch, fed-batch, and continuous fermentation are discussed in relation to inhibition of fermentation in lignocellulosic hydrolysates. (C) 2000 Elsevier Science Ltd. All rights reserved.