Characterization and application of a novel laccase derived from Bacillus amyloliquefaciens

As the copper-containing enzymes, laccases demonstrate a promising potential in various environmental and industrial applications. In this study, a bacterial strain isolated from soil exhibited the laccase activity, which was subsequently characterized and named as Bacillus amyloliquefaciens TCCC 111018. The novel gene encoding CotA-laccase (lac) was amplified using the genome of B. amyloliquefaciens TCCC 111018 as the template and efficiently and actively expressed in Escherichia coli. The recombinant LAC (rLAC) exhibited its highest activity at 80 °C and pH 5.5 for 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) oxidization and 80 °C and pH 7.0 for 2,6-dimethoxyphenol (2,6-DMP) oxidization. rLAC was stable at up to 60 °C and within the pH ranging from 3.0 to 9.0 when using the substrate ABTS. Furthermore, rLAC demonstrated the relatively high tolerance to NaCl, SDS, and most metal ions. Moreover, rLAC was capable of decolorizing the structurally different azo, anthraquinone, and triphenylmethane with different mediator at 60 °C under pH 5.5, 7.0, and 9.0. Therefore, rLAC would be an ideal candidate for lots of biotechnological and industrial applications due to its stability in the extreme conditions, including but not limit to pH, high temperature, halides, heavy metals and detergents.