Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs

Piotr Chylenski, Dejan M. Petrovic, Gerdt Müller, Marie Dahlström, Oskar Bengtsson, Martin Lersch, Matti Siika-aho, Svein Jarle Horn, Vincent G. H. Eijsink

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)

Abstract

Background: Recent advances in the development of enzyme cocktails for degradation of lignocellulosic biomass, especially the discovery of lytic polysaccharide monooxygenases (LPMOs), have opened new perspectives for process design and optimization. Softwood biomass is an abundant resource in many parts of the world, including Scandinavia, but efficient pretreatment and subsequent enzymatic hydrolysis of softwoods are challenging. Sulfite pulping-based pretreatments, such as in the BALI™ process, yield substrates that are relatively easy to degrade. We have assessed how process conditions affect the efficiency of modern cellulase preparations in processing of such substrates. Results: We show that efficient degradation of sulfite-pulped softwoods with modern, LPMO-containing cellulase preparations requires the use of conditions that promote LPMO activity, notably the presence of molecular oxygen and sufficient reducing power. Under LPMO activity-promoting conditions, glucan conversion after 48-h incubation with Cellic® CTec3 reached 73.7 and 84.3% for Norway spruce and loblolly pine, respectively, at an enzyme loading of 8 mg/g of glucan. The presence of free sulfite ions had a negative effect on hydrolysis efficiency. Lignosulfonates, produced from lignin during sulfite pretreatment, showed a potential to activate LPMOs. Spiking of Celluclast®, a cellulase cocktail with low LPMO activity, with monocomponent cellulases or an LPMO showed that the addition of the LPMO was clearly more beneficial than the addition of any classical cellulase. Addition of the LPMO in reactions with spruce increased the saccharification yield from approximately 60% to the levels obtained with Cellic® CTec3. Conclusions: In this study, we have demonstrated the importance of LPMOs for efficient enzymatic degradation of sulfite-pulped softwood. We have also shown that to exploit the full potential of LPMO-rich cellulase preparations, conditions promoting LPMO activity, in particular the presence of oxygen and reducing equivalents are necessary, as is removal of residual sulfite from the pretreatment step. The use of lignosulfonates as reductants may reduce the costs related to the addition of small molecule reductants in sulfite pretreatment-based biorefineries.

Original languageEnglish
Article number177
JournalBiotechnology for Biofuels
Volume10
Issue number1
DOIs
Publication statusPublished - 11 Jul 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Sulfites
Softwoods
sulfite
Polysaccharides
Mixed Function Oxygenases
polysaccharide
Degradation
degradation
Cellulase
Glucans
Reducing Agents
Biomass
hydrolysis
Hydrolysis
Pinus taeda
Enzymes
enzyme
Oxygen
Scandinavian and Nordic Countries
Cellulases

Keywords

  • AA9
  • Biofuel
  • Cellulase
  • GH61
  • Lignocellulose
  • LPMO
  • Pretreatment
  • Pulping
  • Sulfite

Cite this

Chylenski, P., Petrovic, D. M., Müller, G., Dahlström, M., Bengtsson, O., Lersch, M., ... Eijsink, V. G. H. (2017). Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs. Biotechnology for Biofuels, 10(1), [177]. https://doi.org/10.1186/s13068-017-0862-5
Chylenski, Piotr ; Petrovic, Dejan M. ; Müller, Gerdt ; Dahlström, Marie ; Bengtsson, Oskar ; Lersch, Martin ; Siika-aho, Matti ; Horn, Svein Jarle ; Eijsink, Vincent G. H. / Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs. In: Biotechnology for Biofuels. 2017 ; Vol. 10, No. 1.
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abstract = "Background: Recent advances in the development of enzyme cocktails for degradation of lignocellulosic biomass, especially the discovery of lytic polysaccharide monooxygenases (LPMOs), have opened new perspectives for process design and optimization. Softwood biomass is an abundant resource in many parts of the world, including Scandinavia, but efficient pretreatment and subsequent enzymatic hydrolysis of softwoods are challenging. Sulfite pulping-based pretreatments, such as in the BALI™ process, yield substrates that are relatively easy to degrade. We have assessed how process conditions affect the efficiency of modern cellulase preparations in processing of such substrates. Results: We show that efficient degradation of sulfite-pulped softwoods with modern, LPMO-containing cellulase preparations requires the use of conditions that promote LPMO activity, notably the presence of molecular oxygen and sufficient reducing power. Under LPMO activity-promoting conditions, glucan conversion after 48-h incubation with Cellic{\circledR} CTec3 reached 73.7 and 84.3{\%} for Norway spruce and loblolly pine, respectively, at an enzyme loading of 8 mg/g of glucan. The presence of free sulfite ions had a negative effect on hydrolysis efficiency. Lignosulfonates, produced from lignin during sulfite pretreatment, showed a potential to activate LPMOs. Spiking of Celluclast{\circledR}, a cellulase cocktail with low LPMO activity, with monocomponent cellulases or an LPMO showed that the addition of the LPMO was clearly more beneficial than the addition of any classical cellulase. Addition of the LPMO in reactions with spruce increased the saccharification yield from approximately 60{\%} to the levels obtained with Cellic{\circledR} CTec3. Conclusions: In this study, we have demonstrated the importance of LPMOs for efficient enzymatic degradation of sulfite-pulped softwood. We have also shown that to exploit the full potential of LPMO-rich cellulase preparations, conditions promoting LPMO activity, in particular the presence of oxygen and reducing equivalents are necessary, as is removal of residual sulfite from the pretreatment step. The use of lignosulfonates as reductants may reduce the costs related to the addition of small molecule reductants in sulfite pretreatment-based biorefineries.",
keywords = "AA9, Biofuel, Cellulase, GH61, Lignocellulose, LPMO, Pretreatment, Pulping, Sulfite",
author = "Piotr Chylenski and Petrovic, {Dejan M.} and Gerdt M{\"u}ller and Marie Dahlstr{\"o}m and Oskar Bengtsson and Martin Lersch and Matti Siika-aho and Horn, {Svein Jarle} and Eijsink, {Vincent G. H.}",
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Chylenski, P, Petrovic, DM, Müller, G, Dahlström, M, Bengtsson, O, Lersch, M, Siika-aho, M, Horn, SJ & Eijsink, VGH 2017, 'Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs', Biotechnology for Biofuels, vol. 10, no. 1, 177. https://doi.org/10.1186/s13068-017-0862-5

Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs. / Chylenski, Piotr; Petrovic, Dejan M.; Müller, Gerdt; Dahlström, Marie; Bengtsson, Oskar; Lersch, Martin; Siika-aho, Matti; Horn, Svein Jarle; Eijsink, Vincent G. H.

In: Biotechnology for Biofuels, Vol. 10, No. 1, 177, 11.07.2017.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs

AU - Chylenski, Piotr

AU - Petrovic, Dejan M.

AU - Müller, Gerdt

AU - Dahlström, Marie

AU - Bengtsson, Oskar

AU - Lersch, Martin

AU - Siika-aho, Matti

AU - Horn, Svein Jarle

AU - Eijsink, Vincent G. H.

PY - 2017/7/11

Y1 - 2017/7/11

N2 - Background: Recent advances in the development of enzyme cocktails for degradation of lignocellulosic biomass, especially the discovery of lytic polysaccharide monooxygenases (LPMOs), have opened new perspectives for process design and optimization. Softwood biomass is an abundant resource in many parts of the world, including Scandinavia, but efficient pretreatment and subsequent enzymatic hydrolysis of softwoods are challenging. Sulfite pulping-based pretreatments, such as in the BALI™ process, yield substrates that are relatively easy to degrade. We have assessed how process conditions affect the efficiency of modern cellulase preparations in processing of such substrates. Results: We show that efficient degradation of sulfite-pulped softwoods with modern, LPMO-containing cellulase preparations requires the use of conditions that promote LPMO activity, notably the presence of molecular oxygen and sufficient reducing power. Under LPMO activity-promoting conditions, glucan conversion after 48-h incubation with Cellic® CTec3 reached 73.7 and 84.3% for Norway spruce and loblolly pine, respectively, at an enzyme loading of 8 mg/g of glucan. The presence of free sulfite ions had a negative effect on hydrolysis efficiency. Lignosulfonates, produced from lignin during sulfite pretreatment, showed a potential to activate LPMOs. Spiking of Celluclast®, a cellulase cocktail with low LPMO activity, with monocomponent cellulases or an LPMO showed that the addition of the LPMO was clearly more beneficial than the addition of any classical cellulase. Addition of the LPMO in reactions with spruce increased the saccharification yield from approximately 60% to the levels obtained with Cellic® CTec3. Conclusions: In this study, we have demonstrated the importance of LPMOs for efficient enzymatic degradation of sulfite-pulped softwood. We have also shown that to exploit the full potential of LPMO-rich cellulase preparations, conditions promoting LPMO activity, in particular the presence of oxygen and reducing equivalents are necessary, as is removal of residual sulfite from the pretreatment step. The use of lignosulfonates as reductants may reduce the costs related to the addition of small molecule reductants in sulfite pretreatment-based biorefineries.

AB - Background: Recent advances in the development of enzyme cocktails for degradation of lignocellulosic biomass, especially the discovery of lytic polysaccharide monooxygenases (LPMOs), have opened new perspectives for process design and optimization. Softwood biomass is an abundant resource in many parts of the world, including Scandinavia, but efficient pretreatment and subsequent enzymatic hydrolysis of softwoods are challenging. Sulfite pulping-based pretreatments, such as in the BALI™ process, yield substrates that are relatively easy to degrade. We have assessed how process conditions affect the efficiency of modern cellulase preparations in processing of such substrates. Results: We show that efficient degradation of sulfite-pulped softwoods with modern, LPMO-containing cellulase preparations requires the use of conditions that promote LPMO activity, notably the presence of molecular oxygen and sufficient reducing power. Under LPMO activity-promoting conditions, glucan conversion after 48-h incubation with Cellic® CTec3 reached 73.7 and 84.3% for Norway spruce and loblolly pine, respectively, at an enzyme loading of 8 mg/g of glucan. The presence of free sulfite ions had a negative effect on hydrolysis efficiency. Lignosulfonates, produced from lignin during sulfite pretreatment, showed a potential to activate LPMOs. Spiking of Celluclast®, a cellulase cocktail with low LPMO activity, with monocomponent cellulases or an LPMO showed that the addition of the LPMO was clearly more beneficial than the addition of any classical cellulase. Addition of the LPMO in reactions with spruce increased the saccharification yield from approximately 60% to the levels obtained with Cellic® CTec3. Conclusions: In this study, we have demonstrated the importance of LPMOs for efficient enzymatic degradation of sulfite-pulped softwood. We have also shown that to exploit the full potential of LPMO-rich cellulase preparations, conditions promoting LPMO activity, in particular the presence of oxygen and reducing equivalents are necessary, as is removal of residual sulfite from the pretreatment step. The use of lignosulfonates as reductants may reduce the costs related to the addition of small molecule reductants in sulfite pretreatment-based biorefineries.

KW - AA9

KW - Biofuel

KW - Cellulase

KW - GH61

KW - Lignocellulose

KW - LPMO

KW - Pretreatment

KW - Pulping

KW - Sulfite

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U2 - 10.1186/s13068-017-0862-5

DO - 10.1186/s13068-017-0862-5

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JO - Biotechnology for Biofuels

JF - Biotechnology for Biofuels

SN - 1754-6834

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Chylenski P, Petrovic DM, Müller G, Dahlström M, Bengtsson O, Lersch M et al. Enzymatic degradation of sulfite-pulped softwoods and the role of LPMOs. Biotechnology for Biofuels. 2017 Jul 11;10(1). 177. https://doi.org/10.1186/s13068-017-0862-5