Efficient microbial degradation of Toluidine Blue dye by Brevibacillus sp.

Economical and bio-friendly approaches are needed to degrade dye-contaminated wastewater from various industries. In this study, we report on the isolation and characterization of a strain of Brevibacillus that can efficiently degrade Toluidine Blue dye (TB). Eight different bacterial strains which were initially isolated from soil contaminated with Coomassie Brilliant Blue dye (CBB) showed varying degradation rates for CBB. The most efficient isolate was further tested on 7 other dyes; surprisingly, we found this isolate to be much more efficient in degrading TB. Morphological and enzymatic analyses, as well as 16S rRNA sequencing were used to identify this isolate as a species of Brevibacillus. We have characterized the efficiency of TB degradation by this isolate as a function of dye concentration, pH, aeration, as well as nitrogen source. Under optimum conditions, most of the TB could be degraded within 24 h. The biodegradation data for TB were fitted to first-order equation with good correlation.