Identification and Characterization of Azo Dye Decolourizing Bacterial Strains, Alcaligenes faecalis E5.Cd and A. faecalis Fal.3 Isolated from Textile Effluents

The study was designed for isolation and characterization of azo dye decolourizing bacteria which is a prerequisite for developing a microorganism-facilitated treatment of polluting dyes. In this study nine types of bacteria which were able to decolourize three types of azo dyes (Blue H/C, Red 3B and Yellow 3R dye) were isolated from textile effluents collected from Gazipur industrial area in Bangladesh. Depending on 16S rDNA analysis, the most efficient decolourizing bacterium for the Blue H/C and the Red 3B dye was identified as Alcaligenesfaecalis strain E5.Cd while that for the Yellow 3R dye was identified as Alcaligenesfaecalis strain Fal.3. After characterization, both A. faecalis E5.Cdand A. faecalis Fal.3 were found to grow optimally at 35 C and at pH 7 and pH 8, respectively. Both of these strains were sensitive to all antibiotics studied except for Bacitracin. Also, both strains showed maximum decolourization activities after 96 hours incubation in MS media at pH 7 (up to 93%) and pH 8 (up to 94%), at 35 C temperature ( up to 91%), at 50 ppm initial dye concentration (up to 92%), at 20% inoculum size (up to 93%), and at supplementation of 1% co-substrate (up to 93%).