Axenic aerobic biofilms inhibit corrosion of copper and aluminum

The corrosion behavior of unalloyed copper and aluminium alloy 2024 in modi fied Baar's medium has been studied with continuous reactors using electroc hemical impedance spectroscopy. An axenic aerobic biofilm of either Pseudom onas fragi K or Bacillus brevis 18 was able to lessen corrosion as evidence d by a consistent 20-fold increase in the low-frequency impedance value of copper as well as by a consistent four- to sevenfold increase in the polari zation resistance of aluminum 2024 after six days exposure compared to ster ile controls. This is the first report of axenic aerobic biofilms inhibitin g generalized corrosion of copper and aluminum. Addition of the representat ive sulfate-reducing bacterium (SRB) Desulfovibrio vulgaris (to simulate co nsortia corrosion behavior) to either the P. fragi K or B. brevis 18 protec tive biofilm on copper increased the corrosion to that of the sterile contr ol unless antibiotic (ampicillin) was added to inhibit the growth of SRB in the biofilm.