A Systematic Study of the Stress Response Induced by Low pH treatment of Heavily Contaminated Water on Viability and Protein Expression Profiles of E.coli.

Drinking water is one of the most efficient ways to transport a diverse set of pathogens to a vast number of people, resulting in widespread illness, and in some cases death. As such, water quality is a serious public health concern worldwide. Due to their low cost and easy accessibility, common household materials such as vinegar, have been used for water decontamination for decades. However, there are only a small number of systematic and quantitative studies on the efficacy of these methods as well as their impact on the biochemical profile of the pathogens. Escherichia coli (E.coli) is commonly used as an indicator of bacterial contamination due to its prevalence and high mortality rate 1 . In this study, we examined the effects of low pH established by varying concentrations of different acid treatments on E.coli viability and protein expression profiles. A combination of standard culture plating assays and spectroscopic measurements were used to assess viability and determine the minimal acid concentration needed to keep bacterial levels below the EPA's safe drinking water limits. Matrix‐Assisted Laser Desorption Ionization (MALDI) Biotyper was used to analyze changes in the unique protein fingerprint of E.coli harvested at different time points after being subjected to multiple rounds of acid treatment. This work represents the initial step in identifying the E.coli proteins whose expression is altered in response to acid stress. This information would be important in determining if acid stress results in bacterial resistance and if so, help to developing strategies to overcome it.