ABSTRACT
In this work, a novel bacterial strain exhibiting laccase activity was isolated from black liquor and identified as Bacillus subtilis cjp3. The CotA-laccase gene was cloned from strain cjp3 and expressed in Escherichia coli. The purified recombinant laccase has a maximum activity of 7320 U/L, maintaining high stabilities under a wide pH range and high temperature conditions. Nearly no loss of laccase activity was observed even at pH 9.0 after 10 h of incubation. Reactive blue 19, reactive black 5 and indigo carmine could be efficiently decolorized by the purified laccase in the presence of a mediator ABTS. More than 86% of tested dyes were removed in 4 h at pH = 9.0. The recombinant laccase can work well in a broad range of temperatures of 20–80°C(>80% relative activity). These special properties indicated the potential use of the CotA-laccase in treating wastewater containing synthetic dyes.
Funding
This work was supported by the National Natural Science Foundation of China (No.51308300) and the Key Research Program of the Chinese Academy of Sciences (Grant No. KZZD-EW-TZ-13), and partially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).