Decolorization of Textile Azo-metal Complex Dyes by a Halophilic Bacterium Isolated from Camalti Saltern in Turkey

The decolorization of some of azo-metal complex dyes used in textile industry was investigated in this study. The halophilic prokaryotes isolated from a solar sea-saltern (Camalti) in Turkey were screened for resistance to five commercial azo and mixture of azo-metal complex dyes. Only one bacterium was found to be resistant against two of dyes, namely Lanaset Navy R and Lanaset Brown B. The bacterium was identified as Halobacillus sp. C-22 according to 16S rRNA gene sequence analyses. Decolorization experiments were carried out at 120 mg/L concentration of both dyes, at room temperature, and with an acidic pH of 4.5. Lanaset Brown B was decolorized at a high adsorbance ratio (96.12%) at the 78th hour. However, Lanaset Navy R was rapidly decolorized in 10 min (46.67%) and showed the highest adsorbance ratio (60.66%) at the third hour. Freundlich and Langmuir equilibrium isotherm models were used to evaluate the adsorption of dyes and Freundlich isoterm was more suitable for biosorpsiyon of both azo dyes. The functional groups on Halobacillus sp. C-22 for decolorization were characterized by FT-IR. This is the first study to reveal potential of Halobacillus sp. for decolorization of textile azo-metal complex dyes.