Exopolymers which anchor sessile bacteria to metallic surfaces exhibit the capacity to bind copper ions with high affinity. Ionized carboxyl groups on the polymers appear to participate in cupric ion binding. Formation of complexes between the polymers and cupric ions results in the release of protons from the polymer molecule. Attenuated total reflectance Fourier transform infrared spectroscopy showed that polymers composed of acidic polysaccharides promote ionization and deterioration of metallic copper surfaces. X-ray photoelectron spectroscopy studies revealed that the ionic state of the surface-derived copper varied depending on the type of acidic polysaccharide that was in contact with the surface. The results suggest that exopolymers elaborated by adherent bacteria can enhance corrosion of the surfaces with which they are associated.

No abstract

Thin films (3.4 nm) of copper on germanium substrates were exposed to 10% gum arabic aqueous solution, 1% bacterial culture supernatant (BCS) (aqueous and simulated sea water solutions) and 0.5% Pseudomonas utlunticu exopolymer (aqueous and simulated sea water solutions). Pre-and post-exposure characterization were done by Auger electron spectroscopy and x-ray photoelectron spectroscopy. Ancillary graphite furnaaee atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that the copper was oxidized by the gum arabic and BCS, and some was removed from the Cu/Ge interface by all three polymers and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the gum arabic, BCS and Pseudomonus uthticu exopolymer.

Thin films (2.0 nm) of copper on germanium internal reflection elements (IREs) were exposed to 10% gum arabic (aqueous solution), 2% alginic acid (aqueous solution), 1% bacterial culture supernatant (BCS, simulated seawater solution), and 0.5% Pseudomonas atlantica exopolymer (simulated seawater solution) and monitored in situ, real time, with the use of Fourier transform infrared/cylindrical internal reflection/attenuated total reflection spectroscopy as a function of time at ambient conditions. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium IREs. Results indicate that some of the copper was removed from the Cu/Ge interface by all four polymers and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the four polymers in the order of alginic acid < gum arabic < BCS > Pseudomonas atlantica exopolymer. The FT-IR/CIR/ATR technique can be successfully used to monitor biocorrosion systems in in situ, real-time settings.

No abstract