African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12496

Full Length Research Paper

The effect of laccase on cellulase-treated lignin in 1-n-butyl-3-methylimidazolium chloride/H2O homogeneous and H2O heterogeneous solutions

Zhang Yinglong1,2, Zhang Haibo1,3, Zhu Youshuang1 and Huang Feng1*
1State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China. 2Biotechnology Department, Shandong Institute of Commerce and Technology, Jinan 250103, China. 3Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266071, China.
Email: [email protected]

  •  Accepted: 12 October 2011
  •  Published: 30 November 2011

Abstract

In this study, the effect of laccase earlier obtained by our laboratory on cellulase-treated lignin (CEL) in two different solution systems was further investigated. Results obtained were as follows: After laccase treatment of CEL in the heterogeneous water solution, CEL was then compared with control sample A. Ultraviolet (UV) spectra showed that the total absorbance of sample B increased at 205 and 280 nm; Fourier-transform infrared (FTIR) spectra showed that the carbonyl group obviously appeared; and 13C nuclear magnetic resonance (NMR) spectra showed that the C-γ signals disappeared, the C-α signals significantly increased, and the methoxyl content decreased. After laccase treatment of CEL in the [bmim]Cl/H2O homogeneous solution, CEL was compared with control sample C. UV spectra showed that the total absorbance of sample D decreased at 280 nm; high-performance liquid chromatography (HPLC) analysis showed that some small absorption peaks disappeared; and 13C NMR spectra showed that the C-γ signals obviously increased, the C-α signals slightly decreased, while the methoxyl content increased. Clearly, for insoluble CEL in the heterogeneous water solution, laccase partly oxidized the hydroxyl group into a carbonyl group, and thereby partly degraded CEL to increase its solubility. In contrast, for soluble CEL in the [bmim]Cl/H2O homogeneous solution, laccase primarily polymerized small molecule fragments with the CEL macromolecule, increased the methoxyl content of CEL, and thereby played a role in lignin polymerization.

 

Key words: Cellulase-treated lignin, laccase, [bmim]Cl.

Abbreviation

CEL, Cellulase-treated ligninUV, ultraviloet; FTIR, Fourier-transform infraredNMR, nuclear magnetic resonanceHPLC, high-performance liquid chromatographybmim, 1-n-butyl-3-methylimidazolium.