ORIGINAL ARTICLE Electro activated water mechanism on Escherichia coli and Enterococcus faecalis and optimization of operating parameters Ozge Turkay 1 | Mine G. Seker 2 | Salim S. Ramadhan 2 | Anatoli Dimoglo 1 1 Department of Environmental Engineering, Gebze Technical University, Faculty of Engineering, Gebze, Kocaeli 41400, Turkey 2 Department of Molecular Biology and Genetics, Gebze Technical University, Faculty of Science, Gebze, Kocaeli 41400, Turkey Correspondence Ozge Turkay, Department of Environmental Engineering, Gebze Technical University, Faculty of Engineering, Gebze, Kocaeli, 41400, Turkey. Email: oturkay@gtu.edu.tr Funding information The Scientific and Technological Research Council of Turkey (TUBITAK), Grant/Award Number: 113Y572 Abstract In this study, the efficacy of electro activated water (EAW) and its mechanism on Escherichia coli and Enterococcus faecalis were investigated. The effects of different operating parameters of EAW on inactivation of bacteria were evaluated by response surface methodology (RSM). The interac- tion of free chlorine concentration and treatment time at 25 8C had a synergetic effect on E. coli and E. faecalis inactivation. The increase in crystal violet uptake showed the deterioration of cell membrane permeability. The release of 260 nm absorbing materials from both bacteria increased after EAW treatment. Protein degeneration increased with deformation of E. coli and E. faecalis cell membranes, which in turn was followed by the release of proteins together with other intra- cellular components such as DNA, RNA, potassium, and phosphate. Practical applications An electrode module was setup to produce EAW from a mixture of salt and tap water. Freshly pre- pared EAW was added to the bacterial pellets, mixing thoroughly and immediately initiating a timer. The mixtures were set at different treatment times. The effects of three operating parame- ters (treatment time, free chlorine concentration (FCC) and temperature) on bacteria inactivation were investigated using Response surface methodology. Crystal violet uptake assay, 260 nm release study and FT-IR spectroscopy analysis were conducted to determine the mechanism of action of EAW. KEYWORDS cell membrane, electro activated water, Enterococcus faecalis, Escherichia coli, inactivation, respond surface methodology 1 | INTRODUCTION Electro activated water (EAW) is superior water with high oxidation potential that can be used as a disinfectant. The main advantage of EAW is microbial inactivation capacity together with its non-toxic content. EAW can be produced by simply using clean water and salt without the need of other chemical addition (Sharma & Demirci, 2003). Brine water solution is charged inside a reactor resulting in the separation of negative and positive ions of sodium chloride (NaCl) and water (H 2 O) from each other. The ions later recombine to form two new end-products: a mild detergent and a sanitizer/disinfectant, respectively. The detergent is an alkaline solution of sodium hydroxide (NaOH), and the disinfectant (EAW) is an acidic solution of hypochlorous acid (HOCl), a form of free chlorine. EAW also contains other active species such as chlorine dioxide, hydrogen peroxide, and free radicals (Landa-Solis et al., 2005). In recent years, EAW has been used as a disinfection agent against bacteria, viruses and so forth. It is cost-effective, inexpensive and safe, when compared to traditional disinfectants (Ding, Dong, Rahman, & Oh, 2011). Even though sodium hypochlorite has been used as a disin- fectant, it is not healthy for human consumption. However, EAW can be an alternative agent, due to its more stable pH and free chlorine content compared to NaOCl (Kiura et al., 2002). EAW technology has also been used in agriculture (Sharma & Demirci, 2003), medical sterili- zation (Zeng et al., 2010), food safety (Jorquera, Valencia, Eguchi, Katayose, & Riquelme, 2002), as well as in many other areas (Wullaert, 1997). EAW was proved effective in reducing the number of patho- genic bacteria on the surface of vegetables (Izumi, 1999). Venkitanar- ayanan, Ezeike, Hung, and Doyle (1999a) in their study, observed that EAW was able to destroy all microorganisms within 5 min. Suzuki et al. (2002) demonstrated the existence of an inhibitory effect of EAW on J Food Process Preserv. 2017;e13345. https://doi.org/10.1111/jfpp.13345 wileyonlinelibrary.com/journal/jfpp V C 2017 Wiley Periodicals, Inc. | 1 of 9 Received: 17 February 2016 | Revised: 1 March 2017 | Accepted: 2 March 2017 DOI: 10.1111/jfpp.13345