title: Differential gene expression in Staphylococcus aureus exposed to Orange II and Sudan III azo dyes.
abstract: We previously demonstrated the effects of azo dyes and their reduction metabolites on bacterial cell growth and cell viability. In this report, the effects of Orange II and Sudan III on gene expression profiling in Staphylococcus aureus ATCC BAA 1556 were analyzed using microarray and quantitative RT-PCR technology. Upon exposure to 6 μg/ml Orange II for 18 h, 21 genes were found to be differently expressed. Among them, 8 and 13 genes were up- and down-regulated, respectively. Most proteins encoded by these differentially expressed genes involve stress response caused by drug metabolism, oxidation, and alkaline shock indicating that S. aureus could adapt to Orange II exposure through a balance between up and down regulated gene expression. Whereas, after exposure to 6 μg/ml Sudan III for 18 h, 57 genes were differentially expressed. In which, 51 genes were up-regulated and 6 were down-regulated. Most proteins encoded by these differentially expressed genes involve in cell wall/membrane biogenesis and biosynthesis, nutrient uptake, transport and metabolite, and stress response, suggesting that Sudan III damages the bacterial cell wall or/and membrane due to binding of the dye. Further analysis indicated that all differentially expressed genes encoded membrane proteins were up-regulated and most of them serve as transporters. The result suggested that these genes might contribute to survival, persistence and growth in the presence of Sudan III. Only one gene msrA, which plays an important role in oxidative stress resistance, was found to be down-regulated after exposure to both Orange II and Sudan III. The present results suggested that both these two azo dyes can cause stress in S. aureus and the response of the bacterium to the stress is mainly related to characteristics of the azo dyes.
authors.affiliation: Division of Microbiology, National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Rd., Jefferson, AR, 72079-9502, USA.
authors.forename: Hongmiao
authors.initials: H
authors.lastname: Pan
authors.forename: Joshua
authors.initials: J
authors.lastname: Xu
authors.forename: Oh-Gew
authors.initials: OG
authors.lastname: Kweon
authors.forename: Wen
authors.initials: W
authors.lastname: Zou
authors.forename: Jinhui
authors.initials: J
authors.lastname: Feng
authors.forename: Gui-Xin
authors.initials: GX
authors.lastname: He
authors.forename: Carl E
authors.initials: CE
authors.lastname: Cerniglia
authors.forename: Huizhong
authors.initials: H
authors.lastname: Chen
mesh_terms: D001391:Azo Compounds / Q000494:pharmacology*; D001557:Benzenesulfonates / Q000494:pharmacology*; D004396:Coloring Agents / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D004396:Coloring Agents; C033006:sudan III; C014722:2-naphthol orange