Characterization and dye decolorization ability of an alkaline resistant and organic solvents tolerant laccase from Bacillus licheniformis LS04.

A new bacterial strain exhibiting laccase activity was isolated from forest soil and was identified as Bacillus licheniformis LS04. The spore laccase of B. licheniformis LS04 demonstrated a broad pH range for catalyzing substrates. It was quite stable at high temperature and alkaline pH. There was no loss of laccase activity after 10 days incubation at pH 9.0, and about 16% of the initial activity was detected after 10h at 80°C. In addition, the spore laccase was tolerant towards 1M of NaCl and 30% of organic solvents. Reactive black 5, reactive blue 19 and indigo carmine were decolorized by the spore laccase in the absence of mediator. Meanwhile, the decolorization process was efficiently promoted when acetosyringone was present, with more than 80% of color removal in 1h at pH 6.6 or 9.0. The unusual properties indicated a high potential in industrial applications for this novel spore laccase.