Decolorization of Different Azo Dyes and Detoxification of Dyeing Wastewater by Pseudomonas stutzeri (SB_13) Isolated from Textile Dyes Effluent

Aims: The present study aimed to estimate the decolorization of three individual azo dyes or in mixture, as well the decolorization of dyeing wastewater was evaluated using bacterial strain of Pseudomonas stutzeri (SB_13) or bacterial consortium isolated from textile dyes effluent. The cytotoxicity effect of dyeing wastewater and its biodegraded metabolites, as well the detoxification efficacy were evaluated.

Study Design: Soil and water samples were collected from the textile dyeing industrial area for bacterial isolation. Effect of different parameters on the dye decolorization by bacterial strains was optimized.

Place and Duration of Study: The study was performed in Botany & Microbiology Department, Faculty of Science, Al-azhar University, from July 2014 until January 2016.

Methodology: Pseudomonas stutzeri strain (SB_13) was isolated from textile dyes effluent and its ability for decolorization of different azo dyes and detoxification of dyeing wastewater samples was investigated. Comparison the decolorization effectiveness of bacterial strain (SB_13) which was used individually and in a bacterial consortium which contains two previously studied Klebsiella strains of (Klebsiella pneumoniae (Kp) and Klebsiella variicola (Kv)) was also observed. Decolorization of Disperse Blue (R16), Disperse Yellow (D4), and Reactive Red Synozol (R4) dyes which were used singly and in mixture was estimated under different concentrations and incubation conditions.

Results: The highest decolorization rates of single or mixtures of azo dyes were observed with 2% glucose or sucrose, 2% ammonium sulfate, and 3% (v/v) bacterial inoculum size, at pH of 5-7, temperature of 35ºC, and after 72-96 hrs. Mixed cultures of (SB_13 &Kp), (SB_13 &Kv), and (SB_13& Kp& Kv) significantly decolorized 59.5% of Disperse Blue (R16), 52% of Disperse Yellow (D4), and (18.3%) of Reactive Red Synozol (R4) dyes, respectively more than those found by individual strain (SB_13). Individual strain of (SB_13) showed the highest decolorization 61% capacity of azo dyes mixture compared to those observed by bacterial consortiums. The treatment of dyeing wastewater with SB_13 strain significantly reduced the phytotoxicity of wastewater (from 100% of abnormal mitosis to 23.6%) as compared with other treatments.