The virucidal effects of two types of electrolyzed water, acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW), on avian influenza viruses were studied. Virus titers of the highly pathogenic H5N1 virus and the low-pathogenic H9N2 virus irreversibly decreased by >5-log at 1 min after the viruses were mixed with NEW containing 43 ppm free available chlorine (FAC), but not with NEW containing <17 ppm FAC. The minimum concentration of FAC for a virucidal effect of NEW was estimated at around 40 ppm. In contrast, the virus titers decreased by >5 log at 1 min after the viruses were mixed with AEW, in which the concentration of the FAC ranged from 72 to 0 ppm. Thus, the virucidal effect of AEW did not depend on the presence of FAC. Reverse transcription polymerase chain reaction amplified fragments of the M and NP genes, but not the complete M gene, from RNA extracted from the AEW-inactivated virus. Moderate morphological changes were found under the electron microscope, although no changes were observed in the electrophoresed proteins of the AEW-inactivated virus. No viral genes were amplified from the RNA extracted from the NEW-inactivated virus, regardless of the length of the targeted genes. No viral particles were detected under the electron microscope and no viral proteins were detected by electrophoresis for the NEW-inactivated virus. Thus, this study demonstrated potent virucidal effects of AEW and NEW and differences in the virucidal mechanism of the two types of electrolyzed water.

The fungicidal influencing factors of electrolyzed oxidizing water (EOW) on Candida albicans were investigated by suspension quantitative germicidal tests. Results showed that EOW possessed predominant fungicidal rate on C. albican, as high as consummately 100% after 0.5 min duration of 65.5 mg/L active available chlorine concentration (ACC). The fungicidal effect was promoted proportionally along with ACC but was inhibited by organic interferential bovine serum albumin (BSA). The fungicidal mechanism was also investigated at a biological molecular level by detecting series of biochemical indices. Fluorescent microscopy showed that almost all C. albicans cells were stained red in 1 min, suggesting that cell membrane was one of EOW s action targets. Transmission electron microscopy (TEM) showed that EOW destroyed the cellular protective barriers and imposed some damage upon the nucleus area, which verified EOW s effects on microbial ultra-structures. EOW improved membrane permeabilities with the result that the leakages of cellular inclusions (K+, proteins and DNA) and the conductivity increased rapidly. The dehydrogenase relative activities of C. albicans decreased by 44.0% after 10 min, indicating that EOW also had a destructive effect on cellular dehydrogenase.

Glutaraldehyde is used as a disinfectant for endoscopes, but is an irritant and so should be replaced by an alternative. Electrolysed acid water (EAW) has a bactericidal effect, and an endoscopic washing device using EAW has been developed in Japan. To investigate the effect of EAW on the infectivity of viruses, we treated duck hepatitis B virus (DHBV), which has similar properties to hepatitis B virus, with EAW, and determined the number of remaining infectious virus particles in a bioassay system. One-day-old Pekin ducks were inoculated with duck serum containing 105.5 ID50 DHBV; the serum had previously been incubated with 100 volumes of EAW or ion-exchanged water at room temperature for 7 min. DHBV infection was indicated by detection of viral DNA in duck serum samples 1 8 weeks after inoculation. Treatment of serum with EAW diminished DHBV infectivity whereas treatment with ion-exchanged water did not. The virus load was estimated to have been reduced to 101 103 ID50 during the first 1 min and to <100.5 ID50 in the next 6 min of incubation when compared with the control. Thus, EAW directly inactivates DHBV and its clinical application is recommended.

An acidic solution (pH 2.5 2.6) with a high oxidation-reduction potential (ORP; about +1,170 mV) and an alkaline solution (pH 11.5 11.7) with a low ORP (about 880mV) that resulted from electrolysis of 20 mM NaCl (dissolved in a pure water) were tested for their effect on the growth of Streptomyces spp. When spores ( 2 107) were exposed to the electrolyzed solutions (2 ml) for 1 minute, colony formation was totally inhibited by the acidic solution, but little by the alkaline solution although extending the exposure (10 minutes) resulted in a marked inhibition. The 1 minute exposure to their mixture (1:1, v/v) showed a strong inhibition (but weaker than that of the acidic solution). When the unexposed spores were streaked and incubated on ISP No. 4 (inorganic salts - starch medium) agar plate containing a cross density gradient of the acidic and alkaline solutions, a biased growth inhibition toward the acidic solution side was observed although the pH range of the acidic solution end of the plate was around 6.2. It seemed thus unlikely that low pH value contributed to the antimicrobial activity of the acidic solution. It was notable that S. griseus SS-1198 formed a unique morphology on the cross gradient plate. In addition, clear growth inhibition by the acidic solution was observed without direct contact with spores, probably because of chlorine gas release. Acidic solutions (pH 2.6 2.7) resulting from the electrolysis of 20 mM of Na2SO4 show no significant antimicrobial activity when tested by the cross gradient plate method. It thus seemed likely that chlorine played a key role for the antimicrobial activity of the acidic electrolyzed NaCl solution.