Microbial Decolorization of Mixture of Dyes by an Application of Laccase through Bacillus subtillis ETL-1979 Isolated from Soil of Industrial Effluent Treatment Plant

Abstract

The strain bacillus subtillis. ETL-1979 exhibiting laccase activity was screened from industrial effluent treatment plant. The M9 medium containing Cu2+ was used for enriching and isolating bacterial strains capable of oxidizing syringaldazine. One isolated strain was identified as Bacillus subtilis ETL-1979 based on the results of physiological and biochemical tests and 16S rDNA sequence analysis. The strain ETL-1979 could grow at temperatures ranging from 20 to 55˚C and showed optimum growth temperature and pH at 25˚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˚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.