Biofilms of selected bacteria strains were previously used on metal coupons as a protective layer against microbiologically influenced corrosion of metals. Unlike metal surfaces, concrete surfaces present a hostile environment for growing a protective biofilm. The main objective of this research was to investigate whether a beneficial biofilm can be successfully grown on mortar surfaces. Escherichia coli DH5α biofilm was grown on mortar surfaces for 8 days, and the structure and characteristics of the biofilm were studied using advanced microscopy techniques such as scanning electron microscopy and confocal laser scanning microscopy in combination with fluorescence in situ hybridization, live/dead, extracellular polymer staining, ATP analysis, and membrane filtration. A biofilm layer with a varying thickness of 20-40 μm was observed on the mortar surface. The distribution of live and dead bacteria and extracellular polymers varied with depth. The density of the live population near the mortar surface was the lowest. The bacteria reached their highest density at three fourths of the biofilm depth and then decreased again near the biofilm-liquid interface. Overall, the results indicated a healthy biofilm growth in the chosen growth period of 8 days, and it is expected that longer growth periods would lead to formation of a more resistant biofilm with more coverage of mortar surfaces.

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.cemconcomp.2010.02.001 Cement and Concrete Composites, 32, 5, pp. 360-368, 2010-05-01 Modeling the kinetics of corrosion in concrete patch repairs and identification of governing parameters Soleimani, S.; Ghods, P.; Isgor, O. B.; Zhang, J. Y.http://www.nrc-cnrc.gc.ca/irc M ode ling t he k ine t ic s of c orrosion in c onc re t e pa t c h re pa irs a nd ide nt ific a t ion of gove rning pa ra m e t e rs NRCC-53571Soleimani, S.; Ghods, P.; Isgor, O.B.; Zhang, J.Y.; Lounis, Z.

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In this study, Escherichia coli DH5α biofilm was evaluated for its potential to control and minimize microbiologically influenced concrete deterioration (MICD) under mesophilic temperatures (37 °C). Escherichia coli DH5α biofilm was first grown on Portland cement mortar disks for 8 days. Mortar disks were then exposed to two different types of sulfur oxidizing bacteria (SOB) (Thiobacillus neapolitanus and Thiobacillus thiooxidans), which use sulfur compounds as substrate and oxidize them to sulfate and sulfuric acid. The effectiveness of the biofilm against MICD was evaluated by measuring pH, sulfate, calcium concentrations in the reactors and surface analysis of the mortar samples using X-ray diffraction and visual inspection. Overall, the results indicate that the E. coli DH5α biofilm showed good protection against MICD induced by SOB at 37 °C.