The effectiveness of cathodic protection (CP) on microbiologically influenced corrosion (MIC) control

Cathodic protection (CP) is an electrochemical method, to manage corrosion in different industries, especially in buried and sub-merged environments. In those environments microorganisms are present and can cause microbiologically
influenced corrosion (MIC). Most of the industry standards recommend performing CP using -800 mV (Ag/AgCl), however, if microorganisms capable of initiating MIC- are present, for instance sulfate reducing bacteria (SRB), it is
recommended to use even more negative potentials. It is assumed that this will provide adequate protection of the metal. Currently there is no information or valid data in the context of CP, on the level of MIC threat and the extent to
which more negative potentials can be used to provide adequate protection and not over-protection (due to hydrogen embrittlement threat). Conflicting statements can be found in the literature regarding the effectiveness of CP on MIC, from reducing biofilm attachment to increasing bacterial activity and biofilm attachment. Recently, the development and lower price of molecular microbiological methods (MMM) have opened the door for more effective studies of MIC mechanisms along with other electrochemical methods and surface analysis. In this work, the genetic functionality of biofilms formed in the laboratory under CP conditions is investigated using transcriptomics. Gene expression of SRB biofilms under different CP potentials (-800, -850 and -900 mV) will be studied; comparison with control will allow us to distinguish the specific genes that are differentially expressed, leading to a better understanding of the mechanism of CP to affect bacterial activity and diversity.

Keywords - cathodic protection, microbiologically influenced corrosion, molecular microbial method

Acknowledgments
This publication/paper is based upon work from COST Action “CA20130 Euro-MIC” (https://www.euro-mic.org), supported by COST (European Cooperation in Science and Technology). COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career, and innovation.