Biological Degradation of Anthroquinone and Azo Dyes by a Novel Laccase from Lentinus sp

• Published in: Environmental science & technology Vol. 46; no. 9; pp. 5109 - 5117
• Main Authors: Hsu, Chih-An, Wen, Tuan-Nan, Su, Yu-Chang, Jiang, Zhi-Bing, Chen, Chin-Wen, Shyur, Lie-Fen
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.05.2012
• Subjects: Amino acids; Anthraquinones - metabolism; Applied sciences; Azo Compounds - metabolism; Azo Compounds - toxicity; Biodegradation; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Biotechnology; Color; Coloring Agents - metabolism; Coloring Agents - toxicity; Dyes; Environment and pollution; Enzymes; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fungi; Germination; Germination - drug effects; Glycoproteins; Hydrogen-Ion Concentration; Industrial applications and implications. Economical aspects; Industrial wastewaters; Kinetics; Laccase - genetics; Laccase - isolation & purification; Laccase - metabolism; Lentinula - enzymology; Oryza; Phylogeny; Pollution; Seeds - drug effects; Temperature; Textile Industry; Wastewaters; Water treatment and pollution; Discoloration; Organic dye; Enzyme; Anthraquinone dye; Liquid chromatography; Basidiomycota; Biological purification; Fungi; Enzymatic activity; Industrial waste water; Lentinus; Azo dye; Mass spectrometry MS/MS; Oxidoreductases; Waste water purification; Organic compounds; Laccase
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es2047014

This study identifies a new fungal strain, Lentinus sp., that can produce extracellular forms of laccases with an activity of approximately 58 300 U/L. A purified laccase (designated lcc3) was identified by LC-ESI MS/MS as an N-linkage glycosylated protein. The isolated lcc3 cDNA is composed of 1563 bp encoding for a polypeptide of 521 amino acid residues with 4 putative Cu binding regions. Kinetic analyses revealed that the specific activity, k cat, K m, and k cat/K m of lcc3 at pH 2.5 and 70 °C with 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) used as a substrate was 2047 U mg–1, 2017 s–1, 8.4 μM, and 240 s–1 μM–1, respectively. Lcc3 is stable at pH 6.0–10.0 and has a midpoint temperature (T m) of 77.1 °C. We observed 97% decolorization efficiency on Acid Blue 80, 88% on RBBR, and 61% on Acid Red 37 by lcc3. Structural modeling analysis showed that five, four, and three hydrogen bonds can be formed between Acid Blue 80 and Arg178, Arg182, or Asn358; between RBBR and His132, Ser134, or Asp482; and between Acid Red 37 and Arg178, respectively. Notably, Lentinus lcc3 efficiently reversed the toxicity of anthraquinone and azo dyes on rice seed germination and decolorized industrial textile effluent, suggesting the enzyme may be valuable for bioremediation.