Comparison of three deep eutectic solvents and 1-ethyl-3-methylimidazolium acetate in the pretreatment of lignocellulose: effect on enzyme stability, lignocellulose digestibility and one-pot hydrolysis

Ronny Wahlström (Corresponding Author), Jaakko Hiltunen, Mariáh Pitaluga de Souza Nascente Sirkka, Sauli Vuoti, Kristiina Kruus

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

Abstract

Certain ionic liquids (ILs) are well-known pretreatment chemicals for lignocellulosic substrates prior to enzymatic total hydrolysis. Deep eutectic solvents (DESs) are closely related to ILs in many properties, but are easier and on occasion cheaper to synthesize and have been claimed to be less inactivating to enzymes used in the hydrolysis, and less toxic for the environment and to micro-organisms used in fermentation. The use of DESs as lignocellulose pretreatment chemicals has not been studied to a similar extent as the use of ILs. In this study, the stability of three Trichoderma reesei cellulases (the endoglucanases Cel5A and Cel7B and the cellobiohydrolase Cel7A) and one T. reesei xylanase (Xyn11) was compared in concentrated solutions (85% w/w) of three DESs (choline chloride : boric acid in molar ratio 5 : 2, choline chloride : glycerol 1 : 1 and betaine : glycerol 1 : 1) and 1-ethyl-3-methylimidazolium acetate ([EMIM]AcO), a powerful lignocellulose-dissolving IL. The pretreatment efficiency of these chemicals was further compared in a mild pretreatment (90% w/w DES or [EMIM]AcO, 80 °C, 24 h, 5% (w/w) lignocellulose consistency) of four different substrates; microcrystalline cellulose, eucalyptus dissolving pulp, shredded wheat straw and spruce saw dust. After pretreatment, the enzymatic digestibility of the pretreated substrates was evaluated in the enzymatic total hydrolysis in three different setups, including hydrolysis of the washed pretreated substrates in buffer, and of the pretreated substrates in solutions containing 30% (w/w) and 80% (w/w) of DES or [EMIM]AcO. The stability analysis identified glycerol-containing DESs to be highly stabilizing for the cellulases, but their pretreatment efficiency was limited. [EMIM]AcO had a high pretreatment efficiency, but was highly inactivating for the used cellulases. The presence of DES or [EMIM]AcO led in all cases to decreased enzymatic hydrolysis yields. Thus, good enzymatic stability in a certain DES does not directly implicate good performance in the hydrolysis of solid lignocellulosic substrates in that DES.
Original languageEnglish
Pages (from-to)68100-68110
JournalRSC Advances
Volume6
Issue number72
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

Fingerprint

Eutectics
Hydrolysis
Enzymes
Ionic Liquids
Ionic liquids
Cellulases
Acetates
Substrates
Glycerol
Choline
Cellulose 1,4-beta-Cellobiosidase
Betaines
lignocellulose
1-ethyl-3-methylimidazolium
Betaine
Boric acid
Enzymatic hydrolysis
Poisons
Straw
Fermentation

Cite this

@article{12d38792dbee4b1790dd6cd346eb5c35,
title = "Comparison of three deep eutectic solvents and 1-ethyl-3-methylimidazolium acetate in the pretreatment of lignocellulose: effect on enzyme stability, lignocellulose digestibility and one-pot hydrolysis",
abstract = "Certain ionic liquids (ILs) are well-known pretreatment chemicals for lignocellulosic substrates prior to enzymatic total hydrolysis. Deep eutectic solvents (DESs) are closely related to ILs in many properties, but are easier and on occasion cheaper to synthesize and have been claimed to be less inactivating to enzymes used in the hydrolysis, and less toxic for the environment and to micro-organisms used in fermentation. The use of DESs as lignocellulose pretreatment chemicals has not been studied to a similar extent as the use of ILs. In this study, the stability of three Trichoderma reesei cellulases (the endoglucanases Cel5A and Cel7B and the cellobiohydrolase Cel7A) and one T. reesei xylanase (Xyn11) was compared in concentrated solutions (85{\%} w/w) of three DESs (choline chloride : boric acid in molar ratio 5 : 2, choline chloride : glycerol 1 : 1 and betaine : glycerol 1 : 1) and 1-ethyl-3-methylimidazolium acetate ([EMIM]AcO), a powerful lignocellulose-dissolving IL. The pretreatment efficiency of these chemicals was further compared in a mild pretreatment (90{\%} w/w DES or [EMIM]AcO, 80 °C, 24 h, 5{\%} (w/w) lignocellulose consistency) of four different substrates; microcrystalline cellulose, eucalyptus dissolving pulp, shredded wheat straw and spruce saw dust. After pretreatment, the enzymatic digestibility of the pretreated substrates was evaluated in the enzymatic total hydrolysis in three different setups, including hydrolysis of the washed pretreated substrates in buffer, and of the pretreated substrates in solutions containing 30{\%} (w/w) and 80{\%} (w/w) of DES or [EMIM]AcO. The stability analysis identified glycerol-containing DESs to be highly stabilizing for the cellulases, but their pretreatment efficiency was limited. [EMIM]AcO had a high pretreatment efficiency, but was highly inactivating for the used cellulases. The presence of DES or [EMIM]AcO led in all cases to decreased enzymatic hydrolysis yields. Thus, good enzymatic stability in a certain DES does not directly implicate good performance in the hydrolysis of solid lignocellulosic substrates in that DES.",
author = "Ronny Wahlstr{\"o}m and Jaakko Hiltunen and {Pitaluga de Souza Nascente Sirkka}, Mari{\'a}h and Sauli Vuoti and Kristiina Kruus",
note = "SDA: SHP: Bioeconomy",
year = "2016",
doi = "10.1039/c6ra11719h",
language = "English",
volume = "6",
pages = "68100--68110",
journal = "RSC Advances",
issn = "2046-2069",
publisher = "Royal Society of Chemistry RSC",
number = "72",

}

Comparison of three deep eutectic solvents and 1-ethyl-3-methylimidazolium acetate in the pretreatment of lignocellulose: effect on enzyme stability, lignocellulose digestibility and one-pot hydrolysis. / Wahlström, Ronny (Corresponding Author); Hiltunen, Jaakko; Pitaluga de Souza Nascente Sirkka, Mariáh; Vuoti, Sauli; Kruus, Kristiina.

In: RSC Advances, Vol. 6, No. 72, 2016, p. 68100-68110.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Comparison of three deep eutectic solvents and 1-ethyl-3-methylimidazolium acetate in the pretreatment of lignocellulose: effect on enzyme stability, lignocellulose digestibility and one-pot hydrolysis

AU - Wahlström, Ronny

AU - Hiltunen, Jaakko

AU - Pitaluga de Souza Nascente Sirkka, Mariáh

AU - Vuoti, Sauli

AU - Kruus, Kristiina

N1 - SDA: SHP: Bioeconomy

PY - 2016

Y1 - 2016

N2 - Certain ionic liquids (ILs) are well-known pretreatment chemicals for lignocellulosic substrates prior to enzymatic total hydrolysis. Deep eutectic solvents (DESs) are closely related to ILs in many properties, but are easier and on occasion cheaper to synthesize and have been claimed to be less inactivating to enzymes used in the hydrolysis, and less toxic for the environment and to micro-organisms used in fermentation. The use of DESs as lignocellulose pretreatment chemicals has not been studied to a similar extent as the use of ILs. In this study, the stability of three Trichoderma reesei cellulases (the endoglucanases Cel5A and Cel7B and the cellobiohydrolase Cel7A) and one T. reesei xylanase (Xyn11) was compared in concentrated solutions (85% w/w) of three DESs (choline chloride : boric acid in molar ratio 5 : 2, choline chloride : glycerol 1 : 1 and betaine : glycerol 1 : 1) and 1-ethyl-3-methylimidazolium acetate ([EMIM]AcO), a powerful lignocellulose-dissolving IL. The pretreatment efficiency of these chemicals was further compared in a mild pretreatment (90% w/w DES or [EMIM]AcO, 80 °C, 24 h, 5% (w/w) lignocellulose consistency) of four different substrates; microcrystalline cellulose, eucalyptus dissolving pulp, shredded wheat straw and spruce saw dust. After pretreatment, the enzymatic digestibility of the pretreated substrates was evaluated in the enzymatic total hydrolysis in three different setups, including hydrolysis of the washed pretreated substrates in buffer, and of the pretreated substrates in solutions containing 30% (w/w) and 80% (w/w) of DES or [EMIM]AcO. The stability analysis identified glycerol-containing DESs to be highly stabilizing for the cellulases, but their pretreatment efficiency was limited. [EMIM]AcO had a high pretreatment efficiency, but was highly inactivating for the used cellulases. The presence of DES or [EMIM]AcO led in all cases to decreased enzymatic hydrolysis yields. Thus, good enzymatic stability in a certain DES does not directly implicate good performance in the hydrolysis of solid lignocellulosic substrates in that DES.

AB - Certain ionic liquids (ILs) are well-known pretreatment chemicals for lignocellulosic substrates prior to enzymatic total hydrolysis. Deep eutectic solvents (DESs) are closely related to ILs in many properties, but are easier and on occasion cheaper to synthesize and have been claimed to be less inactivating to enzymes used in the hydrolysis, and less toxic for the environment and to micro-organisms used in fermentation. The use of DESs as lignocellulose pretreatment chemicals has not been studied to a similar extent as the use of ILs. In this study, the stability of three Trichoderma reesei cellulases (the endoglucanases Cel5A and Cel7B and the cellobiohydrolase Cel7A) and one T. reesei xylanase (Xyn11) was compared in concentrated solutions (85% w/w) of three DESs (choline chloride : boric acid in molar ratio 5 : 2, choline chloride : glycerol 1 : 1 and betaine : glycerol 1 : 1) and 1-ethyl-3-methylimidazolium acetate ([EMIM]AcO), a powerful lignocellulose-dissolving IL. The pretreatment efficiency of these chemicals was further compared in a mild pretreatment (90% w/w DES or [EMIM]AcO, 80 °C, 24 h, 5% (w/w) lignocellulose consistency) of four different substrates; microcrystalline cellulose, eucalyptus dissolving pulp, shredded wheat straw and spruce saw dust. After pretreatment, the enzymatic digestibility of the pretreated substrates was evaluated in the enzymatic total hydrolysis in three different setups, including hydrolysis of the washed pretreated substrates in buffer, and of the pretreated substrates in solutions containing 30% (w/w) and 80% (w/w) of DES or [EMIM]AcO. The stability analysis identified glycerol-containing DESs to be highly stabilizing for the cellulases, but their pretreatment efficiency was limited. [EMIM]AcO had a high pretreatment efficiency, but was highly inactivating for the used cellulases. The presence of DES or [EMIM]AcO led in all cases to decreased enzymatic hydrolysis yields. Thus, good enzymatic stability in a certain DES does not directly implicate good performance in the hydrolysis of solid lignocellulosic substrates in that DES.

U2 - 10.1039/c6ra11719h

DO - 10.1039/c6ra11719h

M3 - Article

VL - 6

SP - 68100

EP - 68110

JO - RSC Advances

JF - RSC Advances

SN - 2046-2069

IS - 72

ER -