Detoxification of Dilute Acid Hydrolysates of Lignocellulose with Lime

Martı́nez, Alfredo; Rodríguez, Martha Eugenia; Wells, Melissa L.; York, Sean W.; Preston, James F.; Ingram, L. O.

doi:10.1021/bp0001720

Cited by 314 publications

(185 citation statements)

References 39 publications

(60 reference statements)

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“…Recovery and fermentation of sugars from the pretreatment liquid requires either expensive detoxification procedures (overliming, steam stripping, adsorption, ion exchange) or genetically engineered yeast strains [45][46][47] and was therefore not investigated in this bench scale study.…”

Section: Effect Of Alkali Pretreatmentmentioning

confidence: 99%

Potential of Agricultural Residues and Hay for Bioethanol Production

Chen

Sharma-Shivappa

Keshwani

et al. 2007

Appl Biochem Biotechnol

157

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Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62-38.58% glucan, 11.19-20.78% xylan, and 22.01-27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121°C/15 psi for 60 min, 78.10-81.27% of the xylan in untreated feedstocks was solubilized, while 75.09-84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H 2 SO 4 ) solids with Celluclast 1.5 LNovozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme® CP-xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L-cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00-65.82% of the theoretical maximum ethanol yield.

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Section: Effect Of Alkali Pretreatmentmentioning

confidence: 99%

Potential of Agricultural Residues and Hay for Bioethanol Production

Chen

Sharma-Shivappa

Keshwani

et al. 2007

Appl Biochem Biotechnol

157

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“…Among the physical methods, evaporation removes volatile compounds such as acetic acid, furfural and vanillin (Converti et al, 2000). Chemical methods includes different strategies like overliming treatment and use of ion exchange resins and activated charcoal Lee et al, 1999;Martinez et al, 2001;Nilvebrant et al, 2001,). Biological detoxification is substantially based on the enzymatic treatment using peroxidase and laccase obtained from the lignolytic fungus Trametes versicolor (Palmqvist & Hann-Hägerdal, 2000).…”

Section: Inhibitory Compounds Derived From Biomass Pretreatment: Effementioning

confidence: 99%

Latest Frontiers in the Biotechnologies for Ethanol Production from Lignocellulosic Biomass

Paola¹,

Isabella²,

Romano³

2011

Biofuel Production-Recent Developments and Prospects

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“…Inhibitory side products, such as furfural, soluble fragments from lignin, and acetic acid, are formed during dilute acid pretreatment; these compounds retard growth and fermentation. The removal of inhibitors after dilute acid pretreatment typically involves additional process steps, such as fiber separation, countercurrent washing, and overliming (6,7), all of which increase costs. Genetic engineering of resistance into biocatalysts represents a cost-effective approach for inhibitor mitigation.…”

mentioning

confidence: 99%

Plasmidic Expression ofnemAandyafC* Increased Resistance of Ethanologenic Escherichia coli LY180 to Nonvolatile Side Products from Dilute Acid Treatment of Sugarcane Bagasse and Artificial Hydrolysate

Shi

Zheng

Yomano

et al. 2016

Appl Environ Microbiol

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Hydrolysate-resistant Escherichia coli SL100 was previously isolated from ethanologenic LY180 after sequential transfers in AM1 medium containing a dilute acid hydrolysate of sugarcane bagasse and was used as a source of resistance genes. Many genes that affect tolerance to furfural, the most abundant inhibitor, have been described previously. To identify genes associated with inhibitors other than furfural, plasmid clones were selected in an artificial hydrolysate that had been treated with a vacuum to remove furfural. Two new resistance genes were discovered from Sau3A1 libraries of SL100 genomic DNA: nemA (N-ethylmaleimide reductase) and a putative regulatory gene containing a mutation in the coding region, yafC*. The presence of these mutations in SL100 was confirmed by sequencing. A single mutation was found in the upstream regulatory region of nemR (nemRA operon) in SL100. This mutation increased nemA activity 20-fold over that of the parent organism (LY180) in AM1 medium without hydrolysate and increased nemA mRNA levels >200-fold. Addition of hydrolysates induced nemA expression (mRNA and activity), in agreement with transcriptional control. NemA activity was stable in cell extracts (9 h, 37°C), eliminating a role for proteinase in regulation. LY180 with a plasmid expressing nemA or yafC* was more resistant to a vacuum-treated sugarcane bagasse hydrolysate and to a vacuum-treated artificial hydrolysate than LY180 with an empty-vector control. Neither gene affected furfural tolerance. The vacuum-treated hydrolysates inhibited the reduction of N-ethylmaleimide by NemA while also serving as substrates. Expression of the nemA or yafC* plasmid in LY180 doubled the rate of ethanol production from the vacuum-treated sugarcane bagasse hydrolysate. Sugars derived from lignocellulosic residues have the potential to serve as carbohydrate substrates for microbial fermentation into biobased products with minimal impact on food and feed (1-3). However, the deconstruction of lignocellulose and hydrolysis to sugar monomers requires harsh treatments, such as the use of dilute mineral acids at elevated temperatures (4, 5). Inhibitory side products, such as furfural, soluble fragments from lignin, and acetic acid, are formed during dilute acid pretreatment; these compounds retard growth and fermentation. The removal of inhibitors after dilute acid pretreatment typically involves additional process steps, such as fiber separation, countercurrent washing, and overliming (6, 7), all of which increase costs. Genetic engineering of resistance into biocatalysts represents a cost-effective approach for inhibitor mitigation.Furfural is the dominant inhibitor in dilute acid hydrolysates of lignocellulose, a dehydration product of pentose sugars (primarily xylose). Many resistance genes associated with furfural tolerance have been identified for ethanologenic Escherichia coli LY180 and other strains of E. coli (8)(9)(10)(11)(12). Resistant derivatives of ethanologenic E. coli LY180, such as strains EMFR9 (13) and SL100 (20), have be...

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Detoxification of Dilute Acid Hydrolysates of Lignocellulose with Lime

Cited by 314 publications

References 39 publications

Potential of Agricultural Residues and Hay for Bioethanol Production

Potential of Agricultural Residues and Hay for Bioethanol Production

Latest Frontiers in the Biotechnologies for Ethanol Production from Lignocellulosic Biomass

Plasmidic Expression ofnemAandyafC* Increased Resistance of Ethanologenic Escherichia coli LY180 to Nonvolatile Side Products from Dilute Acid Treatment of Sugarcane Bagasse and Artificial Hydrolysate

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