Abstract
Microbiologically influenced corrosion (MIC) is a serious problem that impacts nearly all industries and exacts a severe toll in terms of operating costs, loss of production, deterioration of capital equipment and the consequences of corrosion related failures. While a proactive step, monitoring for MIC-associated microorganisms is often hindered by the fact that sampling methods may not capture key members of the microbial community involved in MIC (sampling biases) and current reliance on conventional culture-dependent methods may underestimate and oversimplify the problem (cultivation bias). Molecular biological tools based on analysis of DNA extracted directly from field samples circumvent the limitations of culture-dependent methods. However, sampling biases must also be addressed in order to ensure that molecular analyses truly provide more accurate and comprehensive MIC evaluation. We have developed a method for sampling layers of a corrosion coupon biofilm using an aramid polymer to capture biofilm organisms as a function of depth while conserving their spatial orientation for a variety of analytical techniques. In the current study, a procedure was developed for DNA extraction from these aramid polymer imprints of layers of a corrosion coupon biofilm. Quantitative polymerase chain reaction (qPCR) was then used to quantify total bacteria and specific microorganisms commonly implicated in MIC. The development of this sampling method and extraction procedure will permit the DNA based analyses (qPCR, microarrays, and even high-throughput sequencing) for the most direct characterization of microbial communities of corrosive biofilms.
