Transcriptional analysis of Escherichia coli during Acid Red 18 decolorization

To comprehensively understand the bio-decolorization process of azo dyes at the molecular level, the transcriptional response of Escherichia coli K-12 to a highly polar azo dye, Acid Red 18 (AR 18), was investigated in this study using whole-genome DNA microarrays. The results showed that genes involved in the reductive decolorization of AR 18 displayed significant upregulation; they were followed by stress response genes. This result indicated that the former genes play more important roles in increasing the AR 18 resistance of E. coli. Moreover, mutants deficient in the functions of yqhD, fdhF, nrfABCD, frdBCD and dmsABC showed lower abilities of decolorizing AR 18 compared with wild type strain, indicating that these genes play important roles in AR 18 decolorization. The above findings reveal that a network of genes is involved in AR 18 decolorization.