Potential of Aeromonas dhakensis in bioremediation of an Azo and Untreated Dye effluent sample

The residual dyes in textile effluents are not efficiently remediated by conventional physical and chemical methods due to the presence of a mixture of compounds, most of which have complex structures. Consequently, the overall environmental impact of textile effluents is a global concern. Biological treatment interventions are currently encouraged since some micro-organisms can utilize dye molecules as a sole source of carbon and nitrogen. In the present study, the dye effluent collected from local industrial areas in Mumbai was screened for bacteria capable of degrading Remazol Deep Black GWF (RDB-GWF) dye. It is a reactive sulphonated diazo dye commonly used in the textile industries. The most promising bacterial strain with dye decolorizing potential was identified as Aeromonas dhakensis based on 16S rRNA gene sequence analysis. A. dhakensis showed optimum decolorization (84.08 %) when 4% inoculum of 0.8 O.D (at 540nm) was added to Luria Bertani (pH 9.0) medium containing 1% NaCl and incubated at 30°C for 24 h under shaker (120rpm) conditions. The strain showed tolerance up to 300ppm dye concentration and significantly decolorized untreated textile effluent sample. The degradation of dye was confirmed by FTIR spectroscopic analysis. Phytotoxicity studies (with Phaseolus mungo and Triticum aestivum) suggested non-toxic nature of degraded metabolites.