Isolation and characterization of distillery spent wash color reducing bacteria and process optimization by Taguchi approach

The ability of five different types of bacterial strains isolated from a distillery mill site was analyzed for decolorization of distillery spent wash. 16S rDNA based denaturing gradient gel electrophoresis (DGGE) and amplified random DNA restriction analysis (ARDRA) were used to characterize the bacterial strains. One of the isolates had higher capability to reduce color (21%) and chemical oxygen demand (COD) (30%) was finally identified by 16S rDNA sequence analysis as Bacillus sp. Different parameters such as pH, temperature, aeration,% carbon,% nitrogen, inoculum size and incubation time were optimized by the Taguchi approach to achieve maximum decolorization of distillery spent wash by the Bacillus sp. Reduction in color (85%) and COD (90%) was observed within 12 h after optimization by the Taguchi method. The significant factor in the optimization process was duration followed by inoculum size to attain maximum color reduction. The Taguchi approach proved to be a reliable tool in optimizing culture conditions and analyzing interaction effects of process parameters in achieving the best possible combination for maximum decolorization of the distillery spent wash.