Enhanced Decolorization Of Azo Dyes By The Quinone Compounds By Sphingomonas Xenophaga QYY And Bacillus Cereus JL

The purpose of this dissertation is to investigate the enhancement of quinone compounds on decolorization of azo dyes by Sphingomonas xenophaga QYY and Bacillus cereus JL. Quinone compounds mediated decolorization of azo dyes by strain QYY and its cytoplasm extracts was studied. Meanwhile, the ability of a newly isolated Bacillus cereus JL to decolorize azo dye under anaerobic and aerobic conditions was investigated. The possible decolorization pathway of Acid Red 3R by strain JL under anaerobic conditions was proposed. Moreover, the characteristics of the decolorization of azo dyes by the combination of strain QYY and strain JL were studied.Anthraquinone-2-sulfonate (AQS) and anthraquinone-2,6- disulfonate (AQDS) as redox mediators can significantly improve the decolorization rate of azo dye Amaranth. And for strain QYY AQS was the most effective quinone redox mediator. But when the concentration of AQS was above 3 mmol/L, the growth of strain QYY was greatly inhibited. The results of flat-count also showed that the AQS had biological toxicity to strain QYY. The decolorization of azo dyes by cytoplasm extracts from strain QYY was studied. There was FMN-dependent azo reductase in the cytoplasm extracts. And such enzyme was capable of decolorizing a variety of azo dyes. Meanwhile, a FMN-dependent AQS reductase was detected.Strain JL is an efficient quinone-mediating dye-decolorization bacterium. It was indentified as Bacillus cereus based on morphological, 16S rDNA and 16S-23S spacer region sequence analysis. The 16S rDNA sequence of strain JL was subimitted to GenBank with the number EU871042.The characteristics of the decolorization of azo dyes by strain JL under anaerobic conditions were investigated. The results demonstrate that the optimal conditions for decolorization of Acid Red 3R are as follows: glucose concentration 1 g/L, pH 6.0, temperature 30℃, inoculation 0.25 g/L. AQS and AQDS as redox mediators greatly improved the decolorization rate of azo dyes. Moreover, AQS was the most effective redox mediator for strain JL. In the presence of AQS, Acid Red 3R is reduced to 4-amino-1-naphthalenesulfonic acid and 7-hydroxy-8-amino-1,3-disulfonate-naphthalene according to the HPLC-MS spectra.Strain JL is also capable of decolorization of azo dyes under aerobic conditions. The optimal conditions for the decolorization of Acid Red 3R are as follows: carbon source is glucose and yeast extract, pH 3-7, temperature 30℃. Under aerobic conditions, strain JL can decolorize a variety of azo dyes.The characteristics of the decolorization of azo dyes by the consortium constructed by the combination of strain QYY and strain JL were studied. The optimal conditions for the decolorization of Acid Red 3R with 0.1 mmol/L AQS are as follows: glucose concentration 0.25 g/L, pH 9.0, temperature around 25-40℃. Moreover, the decolorization rate of Acid Red 3R by the consortium was higher than that by single bacteria.