Biotechnology Bulletin ›› 2022, Vol. 38 ›› Issue (4): 261-268.doi: 10.13560/j.cnki.biotech.bull.1985.2021-0852

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Characterization of Laccase TaLac from Thermus aquaticus and Its Application in Removing Malachite Green Dye

MAO Guo-tao(), WANG Jie, WANG Kai, WANG Fang-yuan, CAO Le-yan, ZHANG Hong-sen, SONG An-dong()   

  1. College of Life Sciences,Henan Agriculture University,Zhengzhou 450002
  • Received:2021-07-06 Online:2022-04-26 Published:2022-05-06
  • Contact: SONG An-dong E-mail:maoguotao@henau.edu.cn;song1666@126.com

Abstract:

To mine the laccases of DUF152 family showing great potential in removing the hazardous dye MG,a candidate from the thermophile Thermus aquaticus(TaLac)was screened by bioinformatics methods,and the recombinant vector pET28a-TaLac was constructed and overexpressed in Escherichia coli. TaLac was purified to study its enzymatic characterization and the ability to decolorize and detoxify MG. The results showed that TaLac contained the conserved copper binding sites of DUF152 family. The purified TaLac with high purity using nickel chelating affinity chromatography catalyzed the oxidation of 2,6-dimethylphenol(DMP),the substrate of typical laccases. The optimal pH,temperature,and Km of TaLac were 5.0,60℃,and 0.74 mmol/L,respectively using DMP as the substrate. Besides,TaLac retained 80% of its original activity after incubation for 4 h at 50℃. TaLac tolerated high concentrations of Mg2+,Ca2+,Mn2+,Zn2+ and Ba2+. Furthermore,TaLac completely decolorized 50 mg/L of MG in 3 h,and completely eliminated the toxicity of MG to Zea mays. Taken together,TaLac is a functional and thermostable laccase of DUF152 family,showing great ability to decolorize and detoxify MG.

Key words: laccase, DUF152 family, Thermus aquaticus, enzymatic characterization, decolorization and detoxification of malachite green