Comparative transcriptomics of the response of Escherichia coli to the disinfectant monochloramine and to growth conditions inducing monochloramine resistance

Proteomic adaptations to starvation prepare Escherichia coli for disinfection tolerance

“…Heat shock proteins (htpG) and oxidative stress response proteins (katG and wrbA) were detected to be up-regulated in chlorine and monochloramine disinfection using microarray (Berry et al 2010, Wang et al 2009). However, several up-regulated genes that were detected using transcriptomics were not detected in this study, for example genes related to ironsulfur cluster assembly, cysteine biosynthesis and antibiotic resistance (Berry et al 2010, Wang et al 2009). This is likely due to the fundamental differences between the transcriptomic and proteomic approaches.…”

“…Relative quantitation of proteins was developed using a label-free method of spectral counting with normalized spectral counts (Liu et al 2004). Proteins expressing ≥ 2-fold change in abundance with p ≤0.05 (Fisher’s exact test on results from the duplicate protein extracts for each treatment combination) were considered as differentially expressed (Berry et al 2010). …”

“…One study shows that upon exposure to 390 mg/L free chlorine, several classes of genes in E. coli were significantly up-regulated, such as genes responsive to oxidative stresses, genes encoding putative oxidoreductases, and genes related to cysteine biosynthesis and ironsulfur cluster systems (Wang et al 2009). Similarly, upon exposure to 1 mg/L monochloramine, E. coli up-regulated genes related to redox responses, oxidoreductase synthesis, and cell envelope integrity response (Berry et al 2010), and the cellular responses were complex and dynamic (Holder et al 2013). Given that mRNA transcripts do not always directly correlate with the expression levels of the encoded proteins due to posttranslational modification (Cox and Mann 2011), there is a need to investigate the cellular response to disinfection at the protein level.…”

Susceptibility of <i>Legionella</i> Strains to the Chlorinated Biocide, Monochloramine

“…Other G2 strains showed moderate monochloramine susceptibilities, suggesting that the observed monochloramine tolerance might be a characteristic of a subgroup of the whole G2 type. Bacterial susceptibility and tolerance to monochloramine could be explained by different membrane compositions (13) or cell responses to biocide exposure (6). To investigate these hypotheses, first it would be useful to better characterise the mode of action of monochloramine on bacterial cells and to determine which sites in the cell are the most affected by the biocide.…”

“…Such a study could be performed by analysing and comparing the transcriptomic responses of susceptible and tolerant strains. Berry et al (6) have defined, by performing a comparative transcriptomic analysis of the response of E. coli to monochloramine, a core set of genes responsible for increased tolerance to stresses, known as the “stressome”. Identifying and comparing the gene expression involved in bacterial tolerance between susceptible and non-susceptible strains would aid our understanding of susceptibility variations within the same bacterial species, as in the case of L. pneumophila species isolated from cooling circuits.…”