Rapid detection of biofilm on corroded copper pipes

Episcopic differential interference contrast (DIC) with UV fluorescence microscopy has been incorporated into a conventional light microscope to view the surface topography of microorganisms, biofilms and opaque substrata surfaces without artefacts. This technique avoids the generation of artefacts produced through preparation for scanning electron microscopy (mainly dehydration) and has been used to investigate microbially influenced corrosion (MIC) in copper and polypropylene pipes from a potable water installation. The copper and polypropylene material examined were obtained from a county hospital in Germany, as well as from test rigs installed in the hospital and in the laboratory where the corrosion process was simulated. Microorganisms such as diatoms and bacteria, were rapidly and reliably detected on and in biofilms on pipe surfaces. The observed biofilm possessed a structure that was neither homogeneous nor confluent over the surface and which ressembled a heterogeneous mosaic of microcolonies.

Key words:

• plumbing tube
• biofilms
• corrosion
• differential interference contrast microscopy
• fluorescence microscopy
• copper corrosion

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