Production of Laccase and Optimization of Its Production by Bacillus sp. Using Distillery Spent Wash as Inducer

ABSTRACT

A bacillus sp. isolated from the sediments of a distillery mill was used for laccase production under optimized culture conditions. The distillery effluent was used as an inducer for overproduction of laccase by employing the Taguchi approach. Screening of different medium components and their effect on laccase production was studied using an M-16 orthogonal array. The formation of laccase was considerably increased by addition of 1 mM copper sulfate (51.95 U/ml), which was further enhanced by the use of different inducers. The usefulness of the Taguchi method for optimization of culture conditions was investigated with five selected factors at four levels, and it was observed that the optimized medium resulted in a 9-fold increase in extracellular laccase production compared with the control. The optimized medium composition for laccase production was dextrose (1%), tryptone (0.1%), CuSO₄ (1 mM), and an inducer (distillery effluent 10% [v/v]) at pH 7, which altogether resulted in 107.32 U/ml extracellular laccase activity. Hence, the Taguchi approach proved to be a reliable tool in optimizing culture conditions and achieving the best possible combination for enhanced laccase production.

KEYWORDS:

• Bacillus sp.
• distillery effluent
• inducers
• laccase
• optimization

ACKNOWLEDGMENTS

We thank Modi Distillery, Modinagar, Uttar Pradesh, India, for providing effluent and sludge during the course of investigation. We thank R. K. Roy (Nutek Inc., USA) for providing a free demo version of their software Qulitek-4. Sincere thanks are also to Dr. Manish Kaushik for his excellent technical assistance in preparing the manuscript.