title: Biocidal effect of cathodic protection on bacterial viability in biofilm attached to carbon steel.
abstract: Biofilm formed on carbon steel by various species of bacterial cells causes serious problems such as corrosion of steel, choking of flow in the pipe, deterioration of the heat-transfer efficiency, and so on. Cathodic protection is known to be a reliable method for protecting carbon steel from corrosion. However, the initial attachment of bacteria to the surface and the effects of cathodic protection on bacterial viability in the biofilm have not been clarified. In this study, cathodic protection was applied to an artificial biofilm containing Pseudomonas aeruginosa (PAO1), a biofilm constituent, on carbon steel. The aims of this study were to evaluate the inhibition effect of cathodic protection on biofilm formation and to reveal the inhibition mechanisms. The viability of PAO1 in artificial biofilm of 5 mm thickness on cathodically protected steel decreased to 1% of the initial cell concentration. Analysis of pH distribution in the artificial biofilm by pH microelectrode revealed that pH in proximity to carbon steel increased to approximately 11 after cathodic protection for 5 h. Moreover, 99% of region in the artificial biofilm was under the pH conditions of over nine. A simulation of pH profile was shown to correspond to experimental values. These results indicate cells in the artificial biofilm were killed or damaged by cathodic protection due to pH increase.
authors.affiliation: Department of Bioengineering, Tokyo Institute of Technology 4259 J2-15 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Miyanaga
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Terashi
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kawai
authors.forename: Hajime
authors.initials: H
authors.lastname: Unno
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Tanji
mesh_terms: D018441:Biofilms; D015169:Colony Count, Microbial; D003343:Corrosion; D004563:Electrochemistry; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D050296:Microbial Viability; D011550:Pseudomonas aeruginosa / Q000254:growth & development* / Q000502:physiology*; D013232:Steel / Q000737:chemistry*
chemical_list: D013232:Steel