Sequential lignin depolymerization by combination of biocatalytic and formic acid/formate treatment steps
Lignin, a complex three-dimensional amorphous polymer, is considered to be a potential natural renewable resource for the production of low-molecular-weight aromatic compounds. In the present study, a novel sequential lignin treatment method consisting of a biocatalytic oxidation step followed by a formic acid-induced lignin depolymerization step was developed and optimized using response surface methodology. The biocatalytic step employed a laccase mediator system using the redox mediator 1-hydroxybenzotriazole. Laccases were immobilized on superparamagnetic nanoparticles using a sorption-assisted surface conjugation method allowing easy separation and reuse of the biocatalysts after treatment. Under optimized conditions, as much as 45 wt% of lignin could be solubilized either in aqueous solution after the first treatment or in ethyl acetate after the second (chemical) treatment. The solubilized products were found to be mainly low-molecular-weight aromatic monomers and oligomers. The process might be used for the production of low-molecular-weight soluble aromatic products that can be purified and/or upgraded applying further downstream processes.
KeywordsLignin Laccase Biocatalysis Depolymerization Formic acid
The support of the Commission for Technology and Innovation of the Swiss Federal Office for Professional Education and Technology (grant PFNM-NM 9632.1), the Swiss National Science Foundation National Research Program 66 (project 4066–136686), ECO-INNOVERA (project IPTOSS), and the Swiss Federal Office for the Environment (FOEN, contract number UTF 410.06.12/IDM 2006.02423.369) is gratefully acknowledged. Special thanks are due to GreenValue SA for providing the lignin used in this study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human and animal rights
This article does not contain any studies with human participants or animals performed by any of the authors.
- Abächerli A, Doppenberg F (1998) Method for preparing alkaline solutions containing aromatic polymers. World Intellectual Property Organization. WO1998042912 A1Google Scholar
- Dyer TJ, Ragauskas AJ (2004) Laccase: a harbinger to kraft pulping. ACS Sym Ser 889:339–362Google Scholar
- Hochstrat R, Wintgens T, Corvini PFX (2015) Immobilised biocatalysts for bioremediation of groundwater and wastewater. IWA Publishing, LondonGoogle Scholar
- Pandey KK, Pitman AJ (2003) FTIR studies of the changes in wood chemistry following decay by brown-rot and white-rot fungi. Int Biodeter Biodeg 52:151–160Google Scholar
- Ruiz-Dueñas FJ, Martínez ÁT (2009) Microbial degradation of lignin: how a bulky recalcitrant polymer is efficiently recycled in nature and how we can take advantage of this. Microb Biotechnol 2:164–177Google Scholar
- Sarkanen KV, Ludwig CH (1971) Lignins: occurrence, formation, structure and reactions. Wiley-Interscience, New YorkGoogle Scholar
- Smith PK, Krohn RI, Hermanson GT, Mallia AK, Gartner FH, Provenzano MD, Fujimoto EK, Goeke NM, Olson BJ, Klenk DC (1985) Measurement of protein using bicinchoninic acid. Anal Biochem 150:76–85Google Scholar
- Wong DWS (2009) Structure and action mechanism of ligninolytic enzymes. Appl Biochem Biotechnol 157:174–209Google Scholar
- Zakzeski J, Bruijnincx PCA, Jongerius AL, Weckhuysen BM (2010) The catalytic valorization of lignin for the production of renewable chemicals. Chem Rev 110:3552–3599Google Scholar