The ability of heated scallop-shell powder (HSSP) to disinfect Escherichia coli ATCC 25922 biofilm was investigated. On account of its cryotolerance and cell surface characteristics, the E. coli strain is reportedly a useful surrogate for E. coli O157: H7 in surface attachment studies. In this study, an E. coli ATCC 25922 biofilm was formed on a glass plate, and immersed in a slurry of HSSP. Following treatment, the disinfection ability of the HSSP toward the biofilm was non-destructively and quantitatively measured by conductimetric assay. The disinfection efficacy increased with HSSP concentration and treatment time. HSSP treatment (10 mg/mL, pH 12.5) for 20 min completely eliminated biofilm bioactivity (approximately 108 CFU/cm2 in non-treated biofilms). In contrast, treatment with NaOH solution at the same pH, and treatment with sodium hypochlorite (200 mg/mL) reduced the activity by approximately one to three log10. Fluorescence microscopy confirmed that no viable cells remained on the plate following HSSP treatment (10 mg/mL). Although alkaline and sodium hypochlorite treatments removed cells from the biofilm, under these treatments, many viable cells remained on the plate. To elucidate the mechanism of HSSP activity against E. coli ATCC 25922, the active oxygen generated from the HSSP slurry was examined by chemiluminescence analysis. The luminescence intensity increased with increasing concentration of HSSP slurry. The results suggested that, besides being alkaline, HSSP generates active oxygen species with sporicidal activity. Thus, HSSP treatment could also be effective for controlling biofilms of the toxic strain E. coli O157: H7, implicated in food poisoning.
 R. M. Donlan and J. W. Costerton, “Biofilms: Survival Mechanisms of Clinically Relevant Microorganism,” Clinical Microbiology Reviews, Vol. 15, No. 2, 2002, pp. 167-193.
 G. Midelet and B. Carpentier, “Transfer of Microorganisms, Including Listeria monocytogenes, from Various Materials to Beef,” Applied and Environmental Microbiology, Vol. 68, No. 8, 2002, pp. 4015-4024.
 K. Matsumura, S. Furukawa, H. Ogihara and Y. Morinaga, “Roles of Multidrug Efflux Pumps on the Biofilm Formation of Escherichia coli K-12,” Biocontrol Science, Vol. 16, No. 2, 2011, pp. 69-72.
 S. Ueda and Y. Kuwabara, “Susceptibility of Biofilm Escherichia coli, Salmonella Enteritidis and Staphylococcus aureus to Detergents and Sanitizers,” Biocontrol Science, Vol. 12, No. 4, 2007, pp. 149-153.
 G. A. Uhlich, P. H. Cooke and E. B. Solomon, “Analysis of the Red-Dry-Rough Phenotype of an Escherichia coli O157:H7 Strain and Its Role in Biofilm Formation and Resistance to Antibacterial Agents,” Applied and Environmental Microbiology, Vol. 72, No. 4, 2006, pp. 2564-2572.
 P. M. Griffin and R. V. Tauxe, “The Epidemiology of Infections Caused by Escherichia coli O157:H7, Other Enterohemorrhagic E. coli, and the Associated Hemolytic Uremic Syndrome,” Epidemiologic Reviews, Vol. 13, No. 1, 1991, pp. 60-98.
 P. I. Tarr, “Escherichia coli O157:H7: Clinical, Diagnostic, and Epidemiological Aspects of Human Infection,” Clinical Infectious Diseases, Vol. 20, No. 1, 1995, pp. 1-10. http://dx.doi.org/10.1093/clinids/20.1.1
 J. Sawai, “Antimicrobial Characteristics of Heated Scallop Shell Powder and Its Application,” Biocontrol Science, Vol. 16, No. 3, 2011, pp. 95-102.
 J. Sawai, H. Igarashi, A. Hashimoto, T. Kokugan and M. Shimizu, “Evaluation of Growth Inhibitory Effect of Ceramics Powder Slurry on Bacteria by Conductance Method,” Journal of Chemical Engineering of Japan, Vol. 28, No. 3, 1995, pp. 288-293.
 J. Sawai, S. Ohashi, H. Miyoshi and H. Shiga, “Killing of Bacillus subtilis Spores by Heated Scallop-Shell Powder Containing Calcium Oxide as the Main Component,” Bokin Bobai, Vol. 35, No. 1, 2007, pp. 3-11. (in Japanese)
 J. Sawai, K. Nagasawa and M. Kikuchi, “Ability of Heated Scallop-Shell Powder to Disinfect Staphylococcus aureus Biofilm,” Food Science and Technology Research, Vol. 19, No. 4, 2013, pp. 561-568.
 T. Bodur and A. Cagri-Mehmetoglu, “Removal of Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7 Biofilms on Stainless Steel Using Scallop Shell Powder,” Food Control, Vol. 25, No. 1, 2012, pp. 1-9.
 J. K. Kim and M. A. Harrison, “Surrogate Selection for Escherichia coli O157:H7 Based on Cryotolerance and Attachment to Romaine Lettuce,” Journal of Food Protection, Vol. 72, No. 7, 2009, pp. 1385-1391.
 G. M. Sapers and J. E. Sites, “Efficacy of 1% Hydrogen Peroxide Wash in Decontaminating Apples and Cantaloupe Melons,” Journal of Food Science, Vol. 68, No. 5, 2003, pp. 1793-1797.
 S. Pao and G. Davies, “Comparing Attachment, Heat Tolerance and Alkali Resistance of Pathogenic and Non-Pathogenic Bacterial Cultures on Orange Surfaces,” Journal of Rapid Methods & Automation in Microbiology, Vol. 9, No. 4, 2001, pp. 271-278.
 S. Duffy, J. Churey, R. W. Worobo and D. W. Schaffner, “Analysis and Modeling of the Variability Associated with UV Inactivation of Escherichia coli in Apple Cider,” Journal of Food Protection, Vol. 63, No. 11, 2000, pp. 1587-1590.
 S. Kohtani, K. Yoshida, T. Maekawa, A. Iwase, A. Kudo, H. Miyabe and R. Nakagaki, “Loading Effects of Silver Oxides upon Generation of Reactive Oxygen Species in Semiconductor Photocatalysis,” Physical Chemistry Chemical Physics, Vol. 10, No. 20, 2008, pp. 2986-2992.
 J. Sawai, E. Kawada, F. Kanou, H. Igarashi, A. Hashimoto, T. Kokugan and M. Shimizu, “Detection of Active Oxygen Generated from Ceramic Powders Having Antibacterial Activity,” Journal of Chemical Engineering of Japan, Vol. 29, No. 4, 1996, pp. 627-633.
 B. Joseph, S. K. Otta and I. Karunasagar, “Biofilm Formation by Salmonella spp. on Food Contact Surfaces and Their Sensitivity to Sanitizers,” International Journal of Food Microbiology, Vol. 64, No. 3, 2001, pp. 367-372.
 V. Leriche and B. Carpentier, “Limitation of Adhesion and Growth of Listeria monocytogenes on Stainless Steel by Staphylococcus sciuri Biofilms,” Journal of Applied Microbiology, Vol. 88, No. 4, 2000, pp. 594-605.
 D. E. Norwood and A. Gilmour, “Adherence of Listeria monocytogenes Strains to Stainless Steel Coupons,” Journal of Applied Microbiology, Vol. 86, No. 4, 1999, pp. 576-582.
 D. Lindsay and A. Holy, “Evaluation of Dislodging Methods for Laboratory-Grown Bacterial Biofilms,” Food Microbiology, Vol. 14, No. 4, 1997, pp. 383-390.
 V. K. Dhir and C. E. R. Dodd, “Susceptibility of Suspended and Surface-Attached Salmonella enteritidis to Biocides and Elevated Temperatures,” Applied and Environmental Microbiology, Vol. 61, No. 5, 1995, pp. 1731-1738.
 B. M. Pitts, A. Hamilton, N. Zelver and S. Stewart, “A Microtiter-Plate Screening Method for Biofilm Disinfection and Removal,” Journal of Microbiological Methods, Vol. 54, No. 2, 2003, pp. 269-276.
 E. Giaouris, N. Chorianopoulos and G. J. E. Nychas, “Effect of Temperature, pH, and Water Activity on Biofilm Formation by Salmonella enterica Enteritidis PT4 on Stainless Steel Surfaces as Indicated by Bead Vortexing Method and Conductance Measurements,” Journal of Food Protection, Vol. 68, No. 10, 2005, pp. 2149-2154.
 K. Jones and S. B. Bradshaw, “Biofilm Formation by Enterobacteriaceae: A Comparison between Salmonella enteritidis, Escherichia coli and a Nitrogen-Fixing Strain of Klebsiella pneumonia,” Journal of Applied Bacteriology, Vol. 80, No. 4, 1996, pp. 458-464.
 J. C. Joaquin, C. Kwan, N. Abramzon, K. Vandervoot and G. B. Marino, “Is Gas-Discharge Plasma a New Solution to the Old Problem of Biofilm Inactivation?” Microbiology, Vol. 155, No. 3, 2009, pp. 724-732.
 E. M. M. Rossoni and C. C. Gaylarde, “Comparison of Sodium Hypochlorite and Peracetic Acid as Sanitizing Agents for Stainless Steel Food Processing Surfaces Using Emifluorescence Microscopy,” International Journal of Food Microbiology, Vol. 61, No. 1, 2000, pp. 81-85.
 S. H. Flint, J. D. Brooks and R. J. Bremer, “Use of the Malthus Conductance Growth Ana1yser to Determine Numbers of Thermophilic Streptococci on Stainless Steel,” Journal of Applied Microbiology, Vol. 83, No. 3, 1997, pp. 335-339.
 M. D. Johnston and M. V. Jones, “Disinfection Tests with Intact Biofilms: Combined Use of the Modified Robbins Device with Impedance Detection,” Journal of Microbiological Methods, Vol. 21, No. 1, 1995, pp. 15-26.
 D. S. Dhaliwal, J. L. Cordier and L. J. Cox, “Impedimetric Evaluation of the Efficiency of Disinfectants against Biofilms,” Letters in Applied Microbiology, Vol. 15, No. 5, 1992, pp. 217-221.
 J. Y. Holah, C. Higgs, S. Robinson, D. Worthington and H. Spenceley, “A Conductance-Based Surface Disinfection Test for Food Hygiene,” Letters in Applied Microbiology, Vol. 11, No. 5, 1990, pp. 25-259.
 T. Cho, “Quorum-Sensing and Mating in Candida albicans Biofilms,” Japanese Journal of Bacteriology, Vol. 64, No. 2, 2009, pp. 331-337. (in Japanese)
 M. E. Shirtliff, J. T. Mader and A. K. Camper, “Molecular Interactions in Biofilms,” Chemistry & Biology, Vol. 9, No. 8, 2002, pp. 859-871.
 M. L. Bari, Y. Inatsu, S. Kawasaki, E. Nazuka and K. Isshiki, “Calcinated Calcium Killing of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on the Surface of Tomatoes,” Journal of Food Protection, Vol. 65, 2002, pp. 1706-1711.
 L. R. Beuchat, “Survival of Enterohemorrhagic Escherichia coli O157:H7 in Bovine Feces Applied to Lettuce and the Effectiveness of Chlorinated Water as a Disinfectant,” Journal of Food Protection, Vol. 62, No. 8, 1999, pp. 845-849.
 M. Abadias, J. Usall, M. Anguera, C. Solsona and I. Viñas, “Microbiological Quality of Fresh, Minimally-Processed Fruit and Vegetables, and Sprouts from Retail Establishments,” International Journal of Food Microbiology, Vol. 123, No. 1-2, 2008, pp. 121-129.
 C. Dong, J. Cairney, O. Sun, O. L. Maddan, G. He and Y. Deng, “Investigation of Mg(OH)2 Nanoparticles as an Antibacterial Agent,” Journal of Nanoparticle Research, Vol. 12, No. 6, 2010, pp. 2101-2109.
 J. Sawai, H. Kojima, H. Igarashi, A. Hashimoto, S. Shoji, A. Takehara, T. Sawaki, T. Kokugan and M. Shimizu, “Escherichia coli Damage by Ceramic Powder Slurries,” Journal of Chemical Engineering of Japan, Vol. 30, No. 6, 1997, pp. 1034-1039.
 A. F. Mendonca, T. I. Amoroso and S. J. Knabel, “Destruction of Gram-Negative Food-Borne Pathogens by High pH Involves Destruction of Cytoplasmic Membrane,” Applied and Environmental Microbiology, Vol. 60, No. 11, 1994, pp. 4009-4014.
 K. Hayashi, M. Hirano, S. Matsuishi and H. Hosono, “Microporous Crystal 12CaO·7Al2O3 Encaging Abundant O¯ Radicals,” Journal of the American Chemical Society, Vol. 124, No. 5, 2002, pp. 738-739.
 P. K. Stoimenov, R. L. Klinger, G. L. Marchin and K. J. Klabunde, “Metal Oxide Nanoparticles as Bactericidal Agents,” Langmuir, Vol. 18, No. 17, 2002, pp. 6679-6686.
 C. J. Hewitt, S. R. Bellara, A. Andreani, G. Nebe-Von-Caron and C. M. Mcfarlane, “An Evaluation of the Anti-Bacterial Action of Ceramic Powder Slurries Using Multi-Parameter Flow Cytometry,” Biotechnology Letters, Vol. 23, No. 9, 2001, pp. 667-675.
 K. Krishnamoorthy, G. Manivannan, S. J. Kim, K. Jeyasubramanian and M. Premanathan, “Antibacterial Activity of MgO Nanoparticles Based on Lipid Peroxidation by Oxygen Vacancy,” Journal of Nanoparticle Research, Vol. 14, No. 9, 2012, pp. 1-10.
 T. Berger, M. Sterrer, S. Stankic, J. Bernardi, O. Diwald and E. Knozinger, “Trapping of Photogenerated Charges in Oxide Nanoparticles,” Materials Science and Engineering: C, Vol. 25, No. 5-8, 2005, pp. 664-668.
 M. Sterrer, O. Diwald and E. Knozinger, “Vacancies and Electron Deficient Surface Anions on the Surface of MgO Nanoparticles,” Journal of Physical Chemistry B, Vol. 104, No. 15, 2000, pp. 3601-3607.