Month: July 2026

Microbially influenced corrosion (MIC) is an operational challenge across industries that rely on pipelines, storage tanks, cooling-water systems, and produced-water infrastructure. It occurs when microorganisms alter conditions at material surfaces, accelerating or redirecting corrosion. Biofilms can create gradients in oxygen and pH, concentrate corrosive metabolites, and mediate reactions with iron, contributing to pitting and other localized damage (Enning and Garrelfs, 2014; Dinh et al., 2004; Deutzmann et al., 2015).

Because several organisms and mechanisms may be involved, microbial monitoring is most useful as part of an integrated corrosion-management program.

How does MIC develop?

Microorganisms can colonize material surfaces and form biofilms that retain nutrients, metabolites, and corrosion products. Conditions within a biofilm may differ sharply from the surrounding fluid, and operational changes can reshape community structure and function (Schwermer et al., 2008). Detection of MIC-associated microorganisms does not, by itself, confirm active corrosion or establish a corrosion rate; results should be interpreted with corrosion coupons or probes, inspection findings, water chemistry, deposit analysis, and operating history (AMPP, 2023).

Why monitor MIC-associated microorganisms?

Routine molecular monitoring helps establish site-specific baselines, track microbial trends, and identify potential hot spots across facilities and sampling locations. It can also support evaluation of mitigation strategies and help prioritize follow-up sampling, inspection, and operational review.

 

Table 1. Key microbial targets in MIC monitoring

Target	What it measures	Relevance to MIC monitoring
Acetic acid-producing bacteria (AAPB)	Organisms that produce acetate and other organic acids.	Can alter local chemistry and contribute to conditions favorable for corrosion.
Sulfate-reducing prokaryotes (SRP)	Anaerobic organisms that reduce sulfate and produce sulfide.	Sulfide, iron-sulfide deposits, and reactions at the metal surface are established MIC mechanisms (Enning and Garrelfs, 2014).
Sulfur-oxidizing bacteria (SOB)	Organisms that oxidize reduced sulfur compounds.	Can generate acidic products and contribute to corrosion where sulfur compounds and oxygen gradients are present (Okabe et al., 2007).
Iron-reducing bacteria (IRB)	Organisms that reduce ferric iron [Fe(III)] to ferrous iron [Fe(II)].	Can alter corrosion-product layers and surface redox chemistry; their effect depends on system conditions (Lee and Newman, 2003).
Highly corrosive methanogens (micH)	Methanogens carrying the micH marker associated with highly corrosive activity.	Provides focused information on methanogens linked to accelerated iron corrosion and electron uptake from iron (Dinh et al., 2004; Deutzmann et al., 2015).
Total prokaryotes (TPK)	A broad measure of prokaryotic abundance.	Provides context for target-specific results and helps track overall microbial load.

 

How PCR supports MIC monitoring

Culture-based methods remain useful but may underrepresent organisms that grow slowly or are difficult to cultivate.  Quantitative real-time PCR (qPCR) and digital PCR (dPCR) detect defined genetic targets directly from extracted DNA, supporting rapid, target-specific testing, semi-quantitative trend analysis by qPCR, quantitative analysis by dPCR, and multiplex detection within a standardized workflow.

Because DNA-based qPCR and dPCR can detect DNA from viable and nonviable cells, results should not be interpreted as a direct measure of microbial activity or corrosion rate. The greatest value comes from consistent sampling and interpretation alongside corrosion and operational data.

A multiplexed approach from GT Molecular

Table 1 summarizes microbial groups commonly considered in MIC monitoring. GT Molecular Real-Time qPCR and Digital PCR Kits are designed to multiplex multiple targets into one reaction, thus reducing reagents, plastics, and pipetting steps for more efficient and cost-effective workflows.  The kits include the primers, probes, and positive controls required for detection.  For real-time PCR kits, the master mix is provided with the reaction, and the control can be serially diluted to generate a standard curve for semi-quantitative analysis. Digital PCR kits are designed to work with specific master mixes from each instrument manufacturer.

By combining target-specific data with a measure of total prokaryotic abundance, the panel supports site-specific baselines and consistent comparisons across samples, locations, and time points. At GT Molecular, we develop molecular tools that help industrial teams add a clear, reproducible microbial perspective to asset-integrity programs.

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