Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.23.219014v1?rss=1 Authors: Lahme, S., Mand, J., Longwell, J., Smith, R., Enning, D. Abstract: Methanogenic archaea have long been implicated in microbially influenced corrosion (MIC) of oil and gas infrastructure, yet a first understanding of the underlying molecular mechanisms has only recently emerged. We surveyed pipeline-associated microbiomes from geographically distinct oil field facilities and found methanogens to account for 0.2 - 9.3% of the sequenced communities. Neither the type nor the abundance of the detected methanogens correlated to the perceived severity of MIC in these pipelines. Using fluids from one pipeline, MIC was reproduced in the laboratory, both under stagnant conditions and in customized corrosion reactors simulating pipeline flow. High corrosion rates (up to 2.43 mm Fe0 yr-1) with macroscopic, localized corrosion features were attributed to lithotrophic, mesophilic microbial activity. Other laboratory tests with the same waters yielded negligible corrosion rates (<0.08 mm Fe0 yr-1). Recently a novel [NiFe] hydrogenase, from Methanococcus maripaludis strain OS7, was demonstrated to accelerate corrosion. We developed a specific qPCR assay and detected the gene encoding the large subunit of this hydrogenase (labelled micH) in corrosive (>0.15 mm Fe0 yr-1) biofilms. The micH gene on the other hand was absent in non-corrosive biofilms despite an abundance of methanogens. Reconstruction of a nearly complete Methanococcus maripaludis genome from a highly corrosive mixed biofilm revealed micH and associated genes in near-identical genetic configuration as strain OS7, thereby supporting our hypothesis that the encoded molecular mechanism contributed to corrosion. Lastly, the proposed MIC biomarker was detected in multiple oil fields, indicating a geographically widespread involvement of this [NiFe] hydrogenase in MIC. Copy rights belong to original authors. Visit the link for more info