School of Bioscience and Engineering, Jadavpur University, Kolkata-700 032, India E-mail: piyalibasak@gmail.com Manuscript received online 01 February 2019, accepted 14 March 2019 A total of ninety strains of bacteria were isolated from several different sources like effluents from tanneries, textile industries, jute mills and dairies; from water samples from a pond, an urban canal, a river and an estuary; from soil samples, and from two common aquatic weeds. All these bacterial strains were checked for their ability to degrade Malachite Green which is heavily used as a colorant in textile and leather industries and is highly toxic, having established carcinogenic and cytotoxic properties. Qualitative assays on solid medium was done to choose dye degraders preliminarily, followed by quantitative assays in liquid medium to estimate their degradation potential in terms of percentage decolorisation. Bacteria showing dye degradation potential have been mostly isolated from industrial effluents, but our study suggests that even some strains isolated from natural water sources have excellent potential as dye degraders and could be effectively used to decolorize waste water in future.