Ethanol Production Using Concentrated Oak Wood Hydrolysates and Methods to Detoxify

Abstract

Ethanol production from concentrated oak wood hydrolysate was carried out to obtain a high ethanol concentration and a high ethanol yield. The effect of added inhibitory compounds, which are typically produced in the pretreatment step of steam-explosion on ethanol fermentation, was also examined. p-Hydroxybenzoic aldehyde, a lignin-degradation product, was the most inhibitory compound tested in this study. Compounds with additional methyl groups had reduced toxicity and the aromatic acids were less toxic than the corresponding aldehydes. The lignin-degradation products were more inhibitory than the sugar-derived products, such as furfural and 5-hydroxymethylfurfural (HMF). Adaptation of yeast cells to the wood hydrolysate and detoxification methods, such as using charcoal and overlime, had some beneficial effects on ethanol production using the concentrated wood hydrolysate. After treatment with charcoal and low-temperature sterilization, the yeast cells could utilize the concentrated wood hydrolysate with 170 as well as 140 g/L glucose, and produce 69.9 and 74.2 g/L ethanol, respectively, with a yield of 0.46-0.48 g ethanol/g glucose. In contrast, the cells could not completely utilize untreated wood hydrolysate with 100 g/L glucose. Low-temperature sterilization, with or without charcoal treatment, was very effective for ethanol production when highly concentrated wood hydrolysates were used. Low-temperature sterilization has advantages over traditional detoxification methods, such as using overlime, ion exchange, and charcoal, because of the reduction in the total cost of ethanol production.

Production of polyhydroxyalkanoates byBurkholderia cepaciaATCC 17759 using a detoxified sugar maple hemicellulosic hydrolysate

“…However, for those treated with low-temperature sterilization (85°C), only a slight increase of total phenolics (less than 8% compared to 33.7% from normal sterilization groups) and a decrease in pH were observed except for samples detoxiWed by overliming, which exhibited decreased total phenolics. These results indicate that low-temperature sterilization, when compared to normal autoclaving, prevented the release of additional phenolic compounds and other acidic inhibitors from soluble lignin [15]. The combination of overliming and low-temperature sterilization resulted in a 65% removal of total phenolics from the original membrane-treated wood hydrolysate.…”

Biological detoxification of different hemicellulosic hydrolysates using Issatchenkia occidentalis CCTCC M 206097 yeast

“…In this paper, the discussions on the phenolic compounds were based on the removal of ferulic acid and syringaldehyde, some of the compounds found at higher concentrations in hemicellulose hydrolysates [10,28]. According to Fig.…”

Effects of some inhibitors on the growth and lipid accumulation of oleaginous yeast Rhodosporidium toruloides and preparation of biodiesel by enzymatic transesterification of the lipid

“…Therefore, a better understanding of the aforementioned inhibitors and how to mitigate their negative effects is crucial [8]. For cellulosic ethanol production, the effects of the inhibitors formed during acid hydrolysis of biomass on the growth of Saccharomyces cerevisiae and ethanol production have been well investigated [8][9][10][11]. It was found that S. cerevisiae can survive at external pH higher than 4.5 and maximum concentration of undissociated acetic acid of \5 g/L [12].…”