Isolation and characterization of dye-degrading bacteria from batik wastewater

Azo dye is typically dye used in batik industries that is toxic to aquatic organisms and humans. Chemical methods can effectively degrade the dye effluent however they produce more toxic compounds. Biological methods offer an alternative that is more environmentally friendly and produce readily degradable compounds. Dye degrading bacteria can degrade the dyes in the effluent under anaerobic for decolorization followed by aerobic condition to produce readily degradable compounds. The batik wastewater sample was collected in Kelantan, Malaysia and was analyzed for COD, pH, and color. The Horikoshi-II media pH 10 was used to propagate growth of bacteria in the dye effluent. The dye degrading bacteria then was isolated from the dye effluent using serial dilution spread plate and streak plate method; One bacterium was finally selected based on faster growth. The specific growth rate and generation time of isolated bacteria were 0.069 h-1 and 14 h respectively. The isolated bacteria have characteristic producing red pigment and gram-positive bacilli. Overall reduction of color and COD by isolated bacteria were 23% and 41% respectively. The isolated bacteria were identified as Bacillus sp. strain ARNZ2707 via 16S rRNA sequence analysis.