Decolourization and Detoxification of Malachite Green by Enterobacter cloacae NAM-9415 Isolated from Flower Vase Water

Document Type : Original Article


Department of Microbiology, Wilson College, Mumbai 400007, Maharashtra, India


Introduction: The appalling environmental hazards associated with the use of a triphenylmethane dye i.e., Malachite Green (MG) was unveiled by the National Institute of Health in 2004. However, in spite of the successful ban of MG in the US, UK, and several European countries, it continues to be the most commonly used dye in microbiological laboratories and a few textile industries. In the present study, the bio-remediation potential of a bacterium isolated from a flower vase filled with traces of MG dye solution was investigated.
Materials and Methods: The physicochemical parameter for degradation of MG was optimized. Also, considering the fact that the dyes are complex molecules and their breakdown products may be unsafe for environmental disposal, toxicity tests were carried out using an aquatic invertebrate (Daphnia magna) as a model organism.
Results: The bacterium was identified as Enterobacter cloacae NAM-9415 by 16S rRNA analysis. It showed 96% decolourization of MG at 500 ppm dye concentration when cultured at optimum conditions of incubation i.e., 15 h at 45 °C under shaker (120 rpm) conditions using nutrient broth medium (pH 7). In addition, it also showed tolerance to high salt concentrations of up to 6g%. Moreover, the breakdown products supported the growth of daphnids in our study.
Conclusions: The above observations indicate the suitability of E. cloacae NAM-9415 for biodecolorization of textile effluents.