Applied Microbiology and Biotechnology

, Volume 55, Issue 6, pp 699–703 | Cite as

Enzymatic modification of kraft lignin through oxidative coupling with water-soluble phenols

  •  M. Lund
  •  A. Ragauskas
Short Communication


The aromatic polymer lignin can be modified through promotion of oxidative coupling between phenolic groups on lignin and various phenols. The reaction is initiated by an oxidation of both components, e.g., by using the oxidoreductases laccase or peroxidase. Coupling between phenolic monomers and lignin has previously been studied by the use of radio-labeled phenols. In this study, incorporation of water-soluble phenols into kraft lignin, using laccase as catalyst, was investigated. Several phenols with carboxylic or sulfonic acid groups were used as markers for the incorporation. The modified lignin was isolated and the amount of phenol incorporated was characterized by means of titration, quantitative 1H-NMR, and quantitative 31P-NMR after modification with 2-chloro-4,4,5,5-tetramethyl-1,2,3-dioxaphospholane. Only a few of the phenols studied were found to be incorporated into lignin. When the phenol guaiacol sulfonate was incorporated into kraft lignin, the lignin became water-soluble at pH 2.4 and a low ionic strength due to the introduction of sulfonic acid groups. The content of sulfonic acid groups in the product was 0.5–0.6 mmol/g lignin. A lower amount of 4-hydroxyphenylacetic acid was incorporated under similar conditions.


Phenol Lignin Ionic Strength Sulfonic Acid Guaiacol 
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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  •  M. Lund
    • 1
  •  A. Ragauskas
    • 2
  1. 1.Chemistry Department, The Royal Veterinary and Agricultural University, 1871 Frederiksberg, Denmark
  2. 2.Institute of Paper Science and Technology, Atlanta, GA 30318, USA

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