Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Bacterial azoreductases are enzymes that decolorize azo dyes via the reductive cleavage of the azo bond. Despite the extensive studies for the identification, isolation and characterization of azoreductases from different bacteria, very minimal research was conducted on the regulation of their gene expression. Since azo dyes are man-made, the physiological roles that azoreductases might play are of particular interest.In an attempt to study the regulation of azoreductases in Escherichia coli, transcriptional data from the Gene Expression Omnibus (GEO) resource were extracted and analyzed to determine how different factors might affect the expression of azoR. Subsequently, using reverse transcription quantitative polymerase chain reaction (RT-qPCR)confirmedsome of these computational predictions. For example, increasing glucose concentration was demonstrated to decreaseazoR expression, whereas increasing culture density increased the expression. Furthermore, azoR expression was significantly higher at an incubation temperature of 30 {uF0B0}C than at 37 {uF0B0}C. Finally, azoR expression significantly decreased whenagitation speed was increased. Similarly, expression data for Pseudomonas aeruginosa were extracted from the GEO and analyzed, and the conditions affecting the expression of azoreductases and azoreductase-like genes in P. aeruginosa were predicted in silico. All genes of interest except paWrbA showed a similar predicted expression pattern at the different studied conditions: Predicted gene expression increased upon growth on minimal media, at late stationary phase with 30 {uF0B0}C incubation using relatively higher agitation speed. Co-expression analysis of azoR in different microarray studies deposited in the GEO was carried out followed by gene clustering based on their functional annotation. Nine genes namely, melA, tpx, yciK, fdnG, fpr, nfsA, nfsB, rutF, and chrR (yieF) were clustered with azoR

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