Isolation and characterization of a novel Bacillus subtilis WD23 exhibiting laccase activity from forest soil

The strain Bacillus sp. WD23 exhibiting laccase activity was screened from forest soil. The M9 medium containing Cu super(2+) was used for enriching and isolating bacterial strains capable of oxidizing syringaldazine. One isolated strain was identified as Bacillus subtilis WD23 based on the results of physiological and biochemical tests and 16S rDNA sequence analysis. The strain WD23 could grow at temperatures ranging from 20 to 55 degree C and showed optimum growth temperature and pH at 25 degree C and 7.0, respectively. The sporulation rate of the strain clearly correlated well with the laccase activity. The temperature half-life of the spore laccase was 2.5 h at 80 degree C and the pH half life time was 15 d at pH 9.0. Its spore laccase could decolorize 50 - 90% of Remazol brilliant blue R (RBBR), alizarin red, congo red, methyl orange and methyl violet, which suggests the potential application of spore laccase in dyestuff treatment.