Biodecolourisation of Azo Dye Reactive Red 22 by Bacillus infantis Strain AAA Isolated from Seawater and Toxicity Assessment of Degraded Metabolites

Decolorization and degradation of Azo dye Reactive Red-22 (RR-22) by a bacterial strain isolated from marine seawater and identified as Bacillus infantis sp. AAA was assessed. Maximum decolorization (95%) of RR-22 (100 mg/L) was achieved at pH 9, 37°C and 3% salt concentration under static conditions in 6h. Various environmental characteristics such as pH, temperature, salt concentration and dye concentration were analysed to determine the optimum decolorization conditions. Decolorization analysis was carried out by UV-vis spectrophotometer. The FTIR spectra showed the absence of -N=N- in the degraded sample. The HPLC chromatogram showed the presence of multiple peaks at different retention times conforming degradation. The phytotoxicity results exhibited the toxic nature of RR-22 compared to the less toxicity of degraded metabolites on seeds of Vigna mungo and Vigna radiata showing 30% and 20% germination.