The antimicrobial effects of ozonated water in a recirculating concurrent reactor were evaluated against four gram-positive and four gram-negative bacteria, two yeasts, and spores of Aspergillus niger. More than 5 log units each of Salmonella typhimurium and Escherichia coli cells were killed instantaneously in ozonated water with or without addition of 20 ppm of soluble starch (SS). In ozonated water, death rates among the gram-negative bacteria-S. typhimurium, E. coli, Pseudomonas aeruginosa, and Yersinia enterocolitica-were not significantly different (P > 0.05). Among gram-positive bacteria, Listeria monocytogenes was significantly P < 0.05) more sensitive than either Staphylococcus aureus or Enterococcus faecalis. In the presence of organic material, death rates of S. aureus compared with L. monocytogenes and E. coli compared with S. typhimurium in ozonated water were not significantly (P > 0.05) affected by SS addition but were significantly reduced (P < 0.05) by addition of 20 ppm of bovine serum albumin (BSA). More than 4.5 log units each of Candida albicans and Zygosaccharomyces bailii cells were killed instantaneously in ozonated water, whereas less than 1 log unit of Aspergillus niger spores was killed after a 5-min exposure. The average ozone output levels in the deionized water (0.188 mg/ml) or water with SS (0.198 mg/ml) did not differ significantly (P < 0.05) but were significantly lower in water containing BSA (0.149 mg/ml). ''The treatment of domestic water to provide a microbiologically safe, aesthetic, potable end product has been normal practice since before the turn of the twentieth century'' (5). Chlorine at low concentrations has been the usual agent of choice in drinking-water purification. At the low concentrations of chlorine used, however, its limitations as a bactericide (3, 4) as well as limitations in its effectiveness against certain eukaryotic pathogens and viruses (18, 20, 21, 25, 27) have been recognized. Furthermore, chlorine at low concentrations may alter certain organic compounds in water producing off tastes and odors as well as forming chloro-organic compounds with carcinogenic potential (22). As an alternative to chlorination in drinking-water disinfection, ozonation of water supplies, which was done first a century ago (29), has become an established means of disinfection and has been reviewed by Rice et al. (25). Bacteria, including Escherichia coli, Staphylococcus aureus, Bacillus cereus, Bacillus megaterium, Salmonella typhimurium, Shigella flexneri, and Vibrio cholerae are sensitive to ozonated water under various conditions (5, 6, 13, 17). Limited information on ozone's effectiveness against bacterial endospores (5, 17) and viruses (6, 20) as well as against eukaryotic pathogens including Cryptosporidium parvum (11, 21, 24) and Giardia lamblia and Giardia muris (12, 31, 32) also exists. The use of ozone in the food industry has been investigated for food preservation, shelf life extension, equipment sterilization, and improvement of food plant effluents (9, 14, 19, 2...

The surface sanitizing properties of a buffered organic acid anionic surfactant (BOAAS) was compared with six traditional sanitizers (organic chlorine - 100 ppm, two iodophors - 25 ppm, peroxyacetic acid - 483 ppm, acid anionic - 230 ppm, and a quaternary ammonium compound - 150 ppm) in its ability to reduce Staphylococcus aureus on an inoculated Formica surface. In the absence of organic material, the traditional sanitizers were not significantly different (P &gt; 0.05) from water in reducing S. aureus at time 0. whereas ≥ 1.2% of the BOAAS reduced a significantly greater (P &lt; 0.05) number of bacteria. When compared with water over 60 min, only the BOAAS significantly reduced (P &lt; 0.05) S. aureus cells. Sixty minutes after exposure, a 1.75% concentration of the BOAAS was &gt; 100× more effective than organic chlorine. Overall, the organic material reduced the effectiveness of the traditional sanitizers and BOAAS. In the presence of 0.5% protein, BOAAS levels ≥ 0.6% significantly (P &lt; 0.05) reduced more S. aureus cells than the quaternary ammonium sanitizer immediately after application. BOAAS concentrations ≥ 0.6% were significantly (P &lt; 0.05) more effective in reducing S. aureus during a 60 min exposure than the organic chlorine sanitizer. In a separate efficacy study, a BOAAS concentration of 0.6% killed &gt;5 logs of S. aureus, Salmonella typhimurium, Pseudomonas aeruginosa and Listeria monocytogenes cells after 30 s exposure.