Mechanisms of laccase-mediator treatments improving the enzymatic hydrolysis of pre-treated spruce

Biotechnology for Biofuels

Ulla Moilanen²  Miriam Kellock³  Anikó Várnai¹  Martina Andberg³  Liisa Viikari² 

[1] Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas N-1432, Norway

[2] Department of Food and Environmental Sciences, University of Helsinki, Helsinki 00014, Finland

[3] VTT Technical Research Centre of Finland, Espoo 02044, Finland

关键词: Spruce;    Cellulose oxidation;    Lignin;    Mediator;    Laccase;    Enzymatic hydrolysis;   

Others  :  1088657
DOI  :  10.1186/s13068-014-0177-8

 received in 2014-10-06, accepted in 2014-12-03,  发布年份 2014

【 摘 要 】

Background

The recalcitrance of softwood to enzymatic hydrolysis is one of the major bottlenecks hindering its profitable use as a raw material for platform sugars. In softwood, the guaiacyl-type lignin is especially problematic, since it is known to bind hydrolytic enzymes non-specifically, rendering them inactive towards cellulose. One approach to improve hydrolysis yields is the modification of lignin and of cellulose structures by laccase-mediator treatments (LMTs).

Results

LMTs were studied to improve the hydrolysis of steam pre-treated spruce (SPS). Three mediators with three distinct reaction mechanisms (ABTS, HBT, and TEMPO) and one natural mediator (AS, that is, acetosyringone) were tested. Of the studied LMTs, laccase-ABTS treatment improved the degree of hydrolysis by 54%, while acetosyringone and TEMPO increased the hydrolysis yield by 49% and 36%, respectively. On the other hand, laccase-HBT treatment improved the degree of hydrolysis only by 22%, which was in the same order of magnitude as the increase induced by laccase treatment without added mediators (19%). The improvements were due to lignin modification that led to reduced adsorption of endoglucanase Cel5A and cellobiohydrolase Cel7A on lignin. TEMPO was the only mediator that modified cellulose structure by oxidizing hydroxyls at the C6 position to carbonyls and partially further to carboxyls. Oxidation of the reducing end C1 carbonyls was also observed. In contrast to lignin modification, oxidation of cellulose impaired enzymatic hydrolysis.

Conclusions

LMTs, in general, improved the enzymatic hydrolysis of SPS. The mechanism of the improvement was shown to be based on reduced adsorption of the main cellulases on SPS lignin rather than cellulose oxidation. In fact, at higher mediator concentrations the advantage of lignin modification in enzymatic saccharification was overcome by the negative effect of cellulose oxidation. For future applications, it would be beneficial to be able to understand and modify the binding properties of lignin in order to decrease unspecific enzyme binding and thus to increase the mobility, action, and recyclability of the hydrolytic enzymes.

【 授权许可】

   
2014 Moilanen et al.; licensee BioMed Central.

【 图 表 】

Figure 1.

Figure 2.

Figure 3.

Figure 4.

Figure 5.

Figure 6.

【 参考文献 】

• [1]Somerville C, Bauer S, Brininstool G, Facette M, Hamann T, Milne J, Osborne E, Paredez A, Persson S, Raab T, Vorwerk S, Youngs H: Toward a systems approach to understanding plant cell walls. Science 2004, 306:2206-2211.
• [2]Himmel ME, Ding SY, Johnson DK, Adney WS, Nimlos MR, Brady JW, Foust TD: Biomass recalcitrance: engineering plants and enzymes for biofuels production. Science 2007, 315:804-807.
• [3]Ramos LP: The chemistry involved in the steam treatment of lignocellulosic materials. Quim Nova 2003, 26:863-871.
• [4]Berlin A, Balakshin M, Gilkes N, Kadla J, Maximenko V, Kubo S, Saddler J: Inhibition of cellulase, xylanase and β-glucosidase activities by softwood lignin preparations. J Biotechnol 2006, 125:198-209.
• [5]Chernoglazov VM, Ermolova OV, Klyosov AA: Adsorption of high-purity endo-1,4-β-glucanases from Trichoderma reesei on components of lignocellulosic materials: cellulose, lignin, and xylan. Enzyme Microb Technol 1988, 10:503-507.
• [6]Converse AO, Ooshima H, Burns DS: Kinetics of enzymatic hydrolysis of lignocellulosic materials based on surface area of cellulose accessible to enzyme and enzyme adsorption on lignin and cellulose. Appl Biochem Biotechnol 1990, 24–25:67-73.
• [7]Ooshima H, Burns DS, Converse AO: Adsorption of cellulase from Trichoderma reesei on cellulose and lignacious residue in wood pretreated by dilute sulfuric acid with explosive decompression. Biotechnol Bioeng 1990, 36:446-452.
• [8]Palonen H, Tjerneld F, Zacchi G, Tenkanen M: Adsorption of Trichoderma reesei CBH I and EG II and their catalytic domains on steam pretreated softwood and isolated lignin. J Biotechnol 2004, 107:65-72.
• [9]Rahikainen J, Mikander S, Marjamaa K, Tamminen T, Lappas A, Viikari L, Kruus K: Inhibition of enzymatic hydrolysis by residual lignins from softwood - study of enzyme binding and inactivation on lignin-rich surface. Biotechnol Bioeng 2011, 108:2823-2834.
• [10]Nakagame S, Chandra RP, Saddler JN: The effect of isolated lignins, obtained from a range of pretreated lignocellulosic substrates, on enzymatic hydrolysis. Biotechnol Bioeng 2010, 105:871-879.
• [11]Solomon EI, Sundaram UM, Machonkin TE: Multicopper oxidases and oxygenases. Chem Rev 1996, 96:2563-2605.
• [12]Thurston CF: The structure and function of fungal laccases. Microbiology 1994, 140:19-26.
• [13]Tadesse MA, D’Annibale A, Galli C, Gentili P, Sergi F: An assessment of the relative contributions of redox and steric issues to laccase specificity towards putative substrates. Org Biomol Chem 2008, 6:868-878.
• [14]Bourbonnais R, Paice MG: Oxidation of non-phenolic substrates: an expanded role for laccase in lignin biodegradation. FEBS Lett 1990, 267:99-102.
• [15]Acunzo F, Galli C, Masci B: Oxidation of phenols by laccase and laccase-mediator systems. Eur J Biochem 2002, 269:5330-5335.
• [16]Bourbonnais R, Leech D, Paice MG: Electrochemical analysis of the interactions of laccase mediators with lignin model compounds. Biochim Biophys Acta 1998, 1379:381-390.
• [17]Fabbrini M, Galli C, Gentili P: Comparing the catalytic efficiency of some mediators of laccase. J Molec Catal B Enzym 2002, 16:231-240.
• [18]Li K, Helm RF, Eriksson KEL: Mechanistic studies of the oxidation of a non-phenolic lignin model compound by the laccase/1-hydroxybenzotriazole redox system. Biotechnol Appl Biochem 1998, 27:239-243.
• [19]Cecchetto A, Fontana F, Minisci F, Recupero F: Efficient Mn-Cu and Mn-Co-TEMPO-catalysed oxidation of alcohols into aldehydes and ketones by oxygen under mild conditions. Tetrahedron Lett 2001, 42:6651-6653.
• [20]De Mico A, Margarita R, Parlanti L, Vescovi A, Piancatelli G: A versatile and highly selective hypervalent iodine (III)/2,2,6,6-tetramethyl-1-piperidinyloxyl-mediated oxidation of alcohols to carbonyl compounds. J Org Chem 1997, 62:6974-6977.
• [21]Galli C, Gentili P: Chemical messengers: mediated oxidations with the enzyme laccase. J Phys Org Chem 2004, 17:973-977.
• [22]Widsten P, Kandelbauer A: Laccase applications in the forest products industry: a review. Enzyme Microb Technol 2008, 42:293-307.
• [23]Kudanga T, Nyanhongo GS, Guebitz GM, Burton S: Potential applications of laccase-mediated coupling and grafting reactions: a review. Enzyme Microb Technol 2011, 48:195-208.
• [24]Mogharabi M, Faramarzi MA: Laccase and laccase‐mediated systems in the synthesis of organic compounds. Adv Synth Catal 2014, 356:897-927.
• [25]Husain Q: Potential applications of the oxidoreductive enzymes in the decolorization and detoxification of textile and other synthetic dyes from polluted water: a review. Crit Rev Biotechnol 2006, 26:201-221.
• [26]Cañas AI, Camarero S: Laccases and their natural mediators: biotechnological tools for sustainable eco-friendly processes. Biotechnol Adv 2010, 28:694-705.
• [27]Camarero S, Ibarra D, Martínez MJ, Martínez ÁT: Lignin-derived compounds as efficient laccase mediators for decolorization of different types of recalcitrant dyes. Appl Environ Microbiol 2005, 71:1775-1784.
• [28]Johannes C, Majcherczyk A: Natural mediators in the oxidation of polycyclic aromatic hydrocarbons by laccase mediator systems. Appl Environ Microbiol 2000, 66:524-528.
• [29]Moilanen U, Kellock M, Galkin S, Viikari L: The laccase-catalyzed modification of lignin for enzymatic hydrolysis. Enzyme Microb Technol 2011, 49:492-498.
• [30]Palonen H, Viikari L: Role of oxidative enzymatic treatments on enzymatic hydrolysis of softwood. Biotechnol Bioeng 2004, 86:550-557.
• [31]Gutiérrez A, Rencoret J, Cadena EM, Rico A, Barth D, del Río JC, Martínez ÁT: Demonstration of laccase-based removal of lignin from wood and non-wood plant feedstocks. Bioresour Technol 2012, 119:114-122.
• [32]Rico A, Rencoret J, del Río JC, Martínez AT, Gutiérrez A: Pretreatment with laccase and a phenolic mediator degrades lignin and enhances saccharification of Eucalyptus feedstock. Biotechnol Biofuels 2014, 7:6. BioMed Central Full Text
• [33]Heap L, Green A, Brown D, van Dongen B, Turner N: Role of laccase as an enzymatic pretreatment method to improve lignocellulosic saccharification. Catal Sci Technol 2014, 4:2251-2259.
• [34]Bragd P, Van Bekkum H, Besemer A: TEMPO-mediated oxidation of polysaccharides: survey of methods and applications. Top Catal 2004, 27:49-66.
• [35]Saito T, Isogai A: TEMPO-mediated oxidation of native cellulose. the effect of oxidation conditions on chemical and crystal structures of the water-insoluble fractions. Biomacromolecules 2004, 5:1983-1989.
• [36]Patel I, Ludwig R, Haltrich D, Rosenau T, Potthast A: Studies of the chemoenzymatic modification of cellulosic pulps by the laccase-TEMPO system. Holzforschung 2011, 65:475-481.
• [37]Horn SJ, Vaaje-Kolstad G, Westereng B, Eijsink VG: Novel enzymes for the degradation of cellulose. Biotechnol Biofuels 2012, 5:1-13. BioMed Central Full Text
• [38]Rahikainen JL, Evans JD, Mikander S, Kalliola A, Puranen T, Tamminen T, Marjamaa K, Kruus K: Cellulase-lignin interactions - the role of carbohydrate-binding module and pH in non-productive binding. Enzyme Microb Technol 2013, 53:315-321.
• [39]Bourbonnais R, Paice MG, Freiermuth B, Bodie E, Borneman S: Reactivities of various mediators and laccases with kraft pulp and lignin model compounds. Appl Environ Microbiol 1997, 63:4627-4632.
• [40]Mattinen M, Maijala P, Nousiainen P, Smeds A, Kontro J, Sipilä J, Tamminen T, Willför S, Viikari L: Oxidation of lignans and lignin model compounds by laccase in aqueous solvent systems. J Molec Catal B 2011, 72:122-129.
• [41]Studer MH, DeMartini JD, Davis MF, Sykes RW, Davison B, Keller M, Tuskan GA, Wyman CE: Lignin content in natural Populus variants affects sugar release. Proc Natl Acad Sci U S A 2011, 108:6300-6305.
• [42]Tamminen TL, Hortling BR: Isolation and characterization of residual lignin. In Advances in Lignocellulosics Characterization. Edited by Argyropoulos DS. Tappi Press, Atlanta; 1999:1-41.
• [43]Wood TM: Preparation of crystalline, amorphous, and dyed cellulase substrates. Meth Enzymol 1988, 160:19-25.
• [44]Rittstieg K, Suurnäkki A, Suortti T, Kruus K, Guebitz G, Buchert J: Investigations on the laccase-catalyzed polymerization of lignin model compounds using size-exclusion HPLC. Enzyme Microb Technol 2002, 31:403-410.
• [45]Suurnäkki A, Tenkanen M, Siika-aho M, Niku-Paavola ML, Viikari L, Buchert J: Trichoderma reesei cellulases and their core domains in the hydrolysis and modification of chemical pulp. Cellulose 2000, 7:189-209.
• [46]Sipos B, Benkő Z, Dienes D, Réczey K, Viikari L, Siika-aho M: Characterisation of specific activities and hydrolytic properties of cell-wall-degrading enzymes produced by Trichoderma reesei Rut C30 on different carbon sources. Appl Biochem Biotechnol 2010, 161:347-364.
• [47]Niku-Paavola ML, Karhunen E, Salola P, Raunio V: Ligninolytic enzymes of the white-rot fungus Phlebia radiata. Biochem J 1988, 254:877-883.
• [48]Lowry OH, Rosebrough NJ, Farr AL, Randall RJ: Protein measurement with the Folin phenol reagent. J Biol Chem 1951, 193:265-275.
• [49]Várnai A, Viikari L, Marjamaa K, Siika-aho M: Adsorption of monocomponent enzymes in enzyme mixture analyzed quantitatively during hydrolysis of lignocellulose substrates. Bioresour Technol 2011, 102:1220-1227.
• [50]Rantanen H, Virkki L, Tuomainen P, Kabel M, Schols H, Tenkanen M: Preparation of arabinoxylobiose from rye xylan using family 10 Aspergillus aculeatus endo-1,4-β-D-xylanase. Carbohydr Polym 2007, 68:350-359.
• [51]Sluiter A, Hames B, Ruiz R, Scarlata C, Sluiter J, Templeton D, Crocker D: Determination of Structural Carbohydrates and Lignin in Biomass. NREL Laboratory Analytical Procedure. [http://www.nrel.gov/biomass/pdfs/42618.pdf]
• [52]Ahlgren PA, Goring DAI: Removal of wood components during chlorite delignification of black spruce. Can J Chem 1971, 49:1272-1275.
• [53]Campbell WG, McDonald IRC: Chemistry of the wood cell wall. II. the isolation of beech and spruce acid-soluble and modified lignins.J Chem Soc 1952:3180–3183.