The present study describes the effect of Pseudomonas aeruginosa on the corrosion rate of nickel-zinc and nickel-copper alloy coatings. The presence of bacteria was associated with decreases in R-ct values, suggesting that P. aeruginosa promoted the corrosion of nickel-copper alloy coatings. However, R-ct values of nickel-zinc coatings increased in response to bacterial inoculation, corresponding to a decrease in corrosion rate for nickel-zinc alloy coatings. Our results suggest that the activity of P. aeruginosa facilitated the corrosion of nickel-copper alloy, while serving a protective function for the nickel-zinc alloy. (C) 2013 Elsevier Ltd. All rights reserved.