Biocidal effect of cathodic protection on bacterial viability in biofilm attached to carbon steel

Department of Bioengineering, Tokyo Institute of Technology 4259 J2-15 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
Biotechnology and Bioengineering (Impact Factor: 4.13). 07/2007; 97(4):850-7. DOI: 10.1002/bit.21278
Source: PubMed


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.

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    • "Settlement of C. rubrum Papers dealing with colonisation on polarised substrata represent a small fraction of the literature on the colonisation of artificial substrata. In particular, several investigations have been performed in order to (i) prevent (antifouling technologies) (Nakasono et al. 1993; Wellman et al. 1996; Miyanaga et al. 2007), (ii) stimulate (restoration strategies) the development of benthic organisms (Hilbertz 1979; Schuhmacher and Shillak 1994; Sternhell et al. 2002; Goreau et al. 2004; Sabater and Yap 2004), and (iii) evaluate the effect of colonisation on cathodic protection (Edyvean et al. 1992; Dexter and Lin 1992; De Saravia et al. 1997; Eashwar et al. 2009). To the authors' knowledge, no studies have been carried out on settlement of octocorals on artificially polarised substrata. "
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    ABSTRACT: Larval settlement of the high value red coral, Corallium rubrum, was studied on three different CaCO(3) substrata, viz. lithogenic (marble), electro-accreted calcium carbonate in the presence and in the absence of cathodic polarisation. The last two substrata consisted of stainless steel plates galvanically coupled with Zn anodes. The electrochemical characterization of the settlement device was studied in order to investigate correlations between cathodic parameters (polarisation potential, current density, calcareous deposit composition) and larval settlement. The results obtained in the natural habitat (at 35 m depth) showed that settlement was five times lower on the electro-accreted aragonite in the presence of low cathodic current densities (i≤1 μA cm(-2)) compared to both marble tiles and electro-accreted aragonite in the absence of polarisation. These last two substrata showed similar settlement values. The implications of these findings on restoration strategies for C. rubrum are discussed.
    Biofouling 08/2011; 27(7):799-809. DOI:10.1080/08927014.2011.604870 · 3.42 Impact Factor
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    • "Alternatively, protective antifouling coatings, such as tributyltin (TBT)-based paints, are used extensively in seawater environments, despite concerns for their toxicity, to combat biofouling and biocorrosion of metallic materials (Jelic-Mrcelic et al., 2006; Yebra et al., 2004). Although cathodic protection has been reported to effectively inhibit biocorrosion of SS by aerobic bacteria (Guezennec, 1994; Miyanaga et al., 2007), it has been found to have no effect on the adhesion of anaerobic bacteria, and is thus unable to prevent the initiation of pitting corrosion by SRB (de Mele et al., 1995). In view of environmental, ecological, and economical impacts, more recent efforts are focused on developing environmentally benign antimicrobial coatings to prevent bacterial adhesion and biofilm formation (Al- Darbi et al., 2002; Sreekumari et al., 2005; Telegdi et al., 2005), as the formation of biofilms is widely recognized as the key step in initiating biocorrosion. "
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    ABSTRACT: To enhance the biocorrosion resistance of stainless steel (SS) and to impart its surface with bactericidal function for inhibiting bacterial adhesion and biofilm formation, well-defined functional polymer brushes were grafted via surface-initiated atom transfer radical polymerization (ATRP) from SS substrates. The trichlorosilane coupling agent, containing the alkyl halide ATRP initiator, was first immobilized on the hydroxylated SS (SS-OH) substrates for surface-initiated ATRP of (2-dimethylamino)ethyl methacrylate (DMAEMA). The tertiary amino groups of covalently immobilized DMAEMA polymer or P(DMAEMA), brushes on the SS substrates were quaternized with benzyl halide to produce the biocidal functionality. Alternatively, covalent coupling of viologen moieties to the tertiary amino groups of P(DMAEMA) brushes on the SS surface resulted in an increase in surface concentration of quaternary ammonium groups, accompanied by substantially enhanced antibacterial and anticorrosion capabilities against Desulfovibrio desulfuricans in anaerobic seawater, as revealed by antibacterial assay and electrochemical studies. With the inherent advantages of high corrosion resistance of SS, and the good antibacterial and anticorrosion capabilities of the viologen-quaternized P(DMAEMA) brushes, the functionalized SS is potentially useful in harsh seawater environments and for desalination plants.
    Biotechnology and Bioengineering 06/2009; 103(2):268-81. DOI:10.1002/bit.22252 · 4.13 Impact Factor
    • "The literature on the interrelationship between cathodic polarization and biofilms, as stated by Little et al. (1999) is rather confusing. Some authors (eg Guezennec 1991; Nekoksa and Gutherman 1991) have reported more bacterial settlement on cathodically protected metals than unpolarized ones, whereas others (eg Videla et al. 1993; Miyanaga et al. 2007) have reported the reverse. Maxwell (1986) did not find variations in biofilm bacterial numbers, but measured reduction of metabolic activity during cathodic polarization . "
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    ABSTRACT: Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about -0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is -1.0 V (SCE).
    Biofouling 02/2009; 25(3):191-201. DOI:10.1080/08927010802670267 · 3.42 Impact Factor
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