Characterization of bacterial consortia involved in the corrosion of gas pipelines using molecular biology techniques

The biofilm collected in a sour gas pipeline was used as an inoculum to develop an anaerobic bacterial consortia in a medium containing sulfate and iron. The formation of a black precipitate of ferrous sulfide indicated the presence of sulfate-reducing bacteria (SRB) in this consortium. The presence of the consortium promoted the formation of pits on the surface of API X52 pipeline steel as observed in Environmental Scanning Electronic Microscopy (ESEM). This behavior was confirmed with the Electrochemical Noise (EN) measurements in which irregular high intensity oscillations were produced with the consortium. An heterogeneous biofilm constituted by bacteria of distinct morphologies was formed on the surface of the metal. Low quality total DNA was obtained from the consortium. However, this genomic material was used to estimate the consortium diversity using the Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the V3 hypervariable region of the 16S rRNA gene obtained by Polymerase Chain Reaction (PCR) amplification. This analysis revealed a diverse consortium probably containing at least 15 different microorganisms.