Decolorization of malachite green by a novel strain of Enterobacter

Department of Chemical Engineering, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata-700 009, India Scottish Church College, I & 3, Urquhart Square, Kolkata-700 006, India E-mail : tina.m@rediffmail.com Manuscript received 02 September 2011, revised 04 January 2012. accepted 09 January 2012 In this study, we have isolated a novel strain of Enterobacter from dye contaminated waste water of West Bengal (Habra) and assessed its capability to remove malachite green (MG), a widely used recalcitrant dye. The dye has been confirmed to be carcinogenic and mutagenic against many organisms. The main objectives of this study were to identify the bacteria, investigate its capability to decolorize malachite green and optimizing the parameters for dye decolorization. The strain was identified to be Enterobacter asburiae strain XJUHX-4TM by 16S rRNA gene analyses. The results showed that this strain demonstrated high decolorizing capability (96-99%) at high concentrations of MG (100-1000 mg/L) under shaking condition within 12 h. The optimum temperature and pH range for dye decolorization were found to be 35-40 ºc and pH 7-8 respectively. The decolorization activity was found to be dye-concentration and inoculum-volume dependent. As the concentration is increased the organism requires more time and more volume of inoculum for decolorization of the dye from the media. Mineral media containing sucrose as carbon source and beef extract as a nitrogen source serve as the best media for decolorization